OPINION EN BANC
TORRUELLA, Circuit Judge.
Plaintiffs-Appellants Associated Builders and Contractors of Massachusetts/Rhode Island, Inc. (“ABC”)1 appeal the decision of the United States District Court for the District of Massachusetts denying ABC’s request for a preliminary injunction. For the reasons stated below, we reverse this decision and remand for action consistent with our opinion.
I. THE FACTS
The Massachusetts Water Resources Authority (“MWRA”) is a governmental agency authorized by the Massachusetts legislature to provide water supply services, sewage collection, and treatment and disposal [347]*347services for the eastern half of Massachusetts. Following a lawsuit arising out of its failure to prevent the pollution of Boston Harbor, United States v. Metropolitan District Commission, C.A. No. 85-0489-MA (Mazzone, J.), the MWRA was ordered to meet a detailed timetable to carry out the clean-up of that body of water. This task, known as the Boston Harbor CleanUp Project (“Project”), is estimated to involve $6.1 billion of public works over a ten year period. The means and methods of carrying out the Project are set forth in the MWRA’s enabling statute, Mass.Gen.Laws ch. 92, App. §§ 1-1, et seq., and the Commonwealth’s public bidding laws. Mass. Gen.Laws ch. 149, §§ 44A-44I and ch. 30, § 39M. Pursuant to these laws, the MWRA provides the funds for construction (assisted by state and federal grants), owns the property to be built, establishes all bid conditions, decides all contract awards, pays the contractors, and generally exercises control and supervision over all aspects of this project.
In the spring of 1988, the MWRA retained Kaiser Engineers, Inc. (“Kaiser”) as its program/construction manager. Kaiser’s primary function is to manage and supervise the ongoing construction activity. In the course of performing its function, however, Kaiser could be expected to employ craft labor in certain situations. Its agreement with the MWRA permits it to act as an execution contractor, or to perform certain direct hire work as needed in cases of default or incomplete performance by other contractors, clean-up work and other limited or emergency situations.
Another important function of Kaiser is to advise the MWRA on the development of a labor relations policy which will maintain worksite harmony, labor-management peaee, and overall stability during the ten-year life of the Project. The MWRA had already experienced work stoppages and informational picketing at various sites2 and was concerned that, because of the scale of the Project and the number of different craft skills involved, it was vulnerable to numerous delays thus placing the court-ordered schedule in jeopardy and subjecting the MWRA to possible contempt orders. This concern was enhanced by the geographic location of the existing and proposed treatment facilities which makes them vulnerable to picketing and other concerted activity.3
The above circumstances led Kaiser to recommend to the MWRA that it be permitted to negotiate with the building and construction trades unions, through the Building and Construction Trades Council and affiliated labor' organizations4 (“Trades Council”), in an effort to arrive at an agreement which would assure labor stability over the life of the Project. Any agreement would be subject to review and final approval by the MWRA.
The MWRA accepted Kaiser’s recommendations and in early May 1989 Kaiser proceeded to meet with negotiating teams from the unions, including the Trades Council. The Master Labor Agreement was the result of their negotiations. After review by the MWRA staff, and upon its recommendation, the MWRA Board of Directors on May 28, 1989 adopted the Master Labor Agreement as the labor policy for the Project and directed that Specification 13.1 be added to the bid specification for all new construction work. Specification 13.1 provides that:
[Ejach successful bidder and any and all levels of subcontractors, as a condition of [348]*348being awarded a contract or subcontract, will agree to abide by the provisions of the Boston Harbor Wastewater Treatment Facilities Project Labor Agreement [“the Master Labor Agreement”] as executed and effective May 22, 1989, by and between [Kaiser], on behalf of [MWRA], and the [Trades Council] ... and will be bound by the provisions of that agreement in the same manner as any other provision of the contract. A copy of the agreement is attached and included as part of these Contract Documents ...
The Master Labor Agreement establishes as “the policy of the [MWRA] that the construction work covered by this Agreement shall be contracted to Contractors who agree to execute and be bound by the terms of this Agreement.” It is the duty of Kaiser on behalf of MWRA to “monitor compliance with this Agreement by all Contractors who through their execution of this Agreement, together with their subcontractors, have become bound hereto.” The parties state the need to meet the “specified and limited time frames” established by the district court’s order in the Boston Harbor Clean-up case. Also agreed to are binding methods for the settlement of “all misunderstandings, disputes or grievances which may arise [and] ... the Union, agree[s] not to engage in any strike, slowdown or interruption of work [or] the [employers] ... to engage in any lockout.”
Most importantly, the Trades Council is recognized “as the sole and exclusive bargaining representative of all craft employees,” and its hiring halls are made the initial and principal source for the Project’s labor force. All employees are subject to the union security provisions of the agreement which require that they become union members within seven days of their employment. Employees may seek redress for their grievances only through the recognized labor organizations, and the contractors are bound by the Trades Council member unions’ wage and benefit provisions and apprenticeship program. The contractors are required to make contributions to various union benefit trust funds and to observe the unions’ work rules and job classifications.
The Master Labor Agreement became “effective [on] May 22, 1989, and shall continue in effect for the duration of the Project construction work.” As previously indicated, the Project is expected to take ten years to complete.
II. PROCEDURAL BACKGROUND
ABC is an organization composed of individual construction contractors and trade associations representing over 18,000 “merit shop” (i.e., non-union) construction industry employers. On March 5, 1990, ABC brought suit in the United States District Court for the District of Massachusetts against the MWRA, Kaiser and the Trades Council, seeking injunctive relief against enforcement of bidding Specification 13.1. ABC claims that, as applied to its membership, Specification 13.1 effectively bars them from seeking and obtaining any bids in this multi-billion dollar, ten-year endeav- or. ABC alleges irreparable injury and damages from what it perceives to be a violation of various federal and state statutes. These contentions, and the district court’s treatment of them, can be summarized as follows:
(1) Preemption under the NLRA. ABC alleged that the National Labor Relations Act (“NLRA” or “Act”), 29 U.S.C. § 151 et seq., prohibits the MWRA from interfering with the labor negotiations process, specifically arguing that requiring employers to accept the terms of a collective bargaining agreement with a union that has not been designated as the bargaining agent by employees is illegal. The district court held that Section 8(e) and (f) of the NLRA5 permit such restrictive agreements in the construction industry and that even if the Master Labor Agreement were to affect NLRA-regulated conduct, such impact must be considered against the manifest importance of the Boston Harbor clean-up. “The presence of non-represented employees simply increases the potential for continuous strife and crippling work stoppag[349]*349es.” The court ruled that the Master Labor Agreement was lawful under the circumstances.
(2) Preemption under ERISA. ABC claimed that since the Agreement required employers to contribute to trust funds, the Agreement in effect regulated the terms and conditions of employee benefit plans covered under Section 514(c) of the Employee Retirement Income Security Act (“ERISA”), 29 U.S.C. § 1144(c). The court disagreed, holding that the Agreement is not so broad and only applies to a single discrete project and thus does not contravene ERISA.
(3) Equal protection and due process clause allegations. ABC claimed that the bidding procedures discriminate against non-union contractors and effectively preclude such contractors from bidding, thus violating the equal protection and due process clauses. These claims were also rejected by the district court, which ruled that non-union contractors are not a protected class, that bidding procedures were open to all contractors, and that since ABC had failed to make any bid as of yet, a constitutionally protected right was lacking.6
(4) The Sherman Act claim. ABC alleged that the Master Labor Agreement and Specification 13.1 constitute a conspiracy among appellees to reduce competition in the construction industry by effectively precluding non-union contractors, in violation of the Sherman Act, 15 U.S.C. § 1. Below, the court reiterated that appellants were not excluded from the bidding process and furthermore, since the Master Labor Agreement “serves legitimate business, and public purposes” there was no antitrust violation. Moreover, the district court found that the MWRA, as a state entity, is immune from an anti-trust claim and that Section 8(e) of the NLRA along with labor’s non-statutory anti-trust exemption under the Sherman Act protect Kaiser and the Trades Council as well.
(5) State law claims. The district court rejected ABC’s state law violations claim, ruling that the Massachusetts Public Bidding statute, Mass.Gen.Laws eh. 30, § 39M and ch. 149, §§ 44A-I, specifically required that the winning bidder must furnish labor that can work in “harmony with all the other elements of labor employed or to be employed on the work.” It further ruled that there was no interference with business relationships because no relationships existed as of yet.
Thus, the district court denied a preliminary injunction holding that, first, the appellants were not likely to succeed on the merits. Second, ABC had not shown immediate and irreparable harm because it had not been awarded a contract; even if it had, it would have an adequate remedy at law. Third, the balance of harm to the appellants was outweighed by the harm to the appellees, since the appellees would suffer intolerable delays, disruptions, and increased costs in the Boston Harbor cleanup without Specification 13.1. And last, issuing an injunction would adversely affect the public interest in the swift clean-up of Boston Harbor.
ABC appealed the denial of the preliminary injunction to a panel of this court. In its opinion, the original panel reached only the issue of preemption under the NLRA, finding (as do we) that issue dispositive of the appeal. In its petition for rehearing en banc, the Trades Council raised a new point relevant to NLRA preemption: whether Specification 13.1 should escape preemption because it was necessary to efficient completion of the clean-up. The Trades Council, joined by the MWRA and various amici in their briefs on rehearing, maintain that because the Specification was enacted to further proprietary, rather than regulatory, interests, it falls within an exception to the preemption doctrine allegedly articulated by the Supreme Court in Wisconsin Dep’t of Indus. v. Gould, 475 U.S. 282, 106 S.Ct. 1057, 89 L.Ed.2d 223 (1986). We determined that this issue merited closer scrutiny by the court as a whole, and issued an order requesting the parties to address the following issues:
[350]*350Is the MWRA’s insistence upon the labor conditions at issue reasonably related to an important proprietary interest of the state, a legitimate response to state procurement restraints, or a legitimate response to local economic needs?
If so, is that insistence therefore lawful, Wisconsin Dep’t of Industry v. Gould, 475 U.S. 282, 291 [106 S.Ct. 1057, 1063, 89 L.Ed.2d 223] (1986) and Golden State Transit Corp. v. City of Los Angeles, 475 U.S. 608 [106 S.Ct. 1395, 89 L.Ed.2d 616] (1986), being distinguishable in this respect?
III. STANDARD OF REVIEW
On review, we will reverse the district court’s denial of a preliminary injunction where the denial is an abuse of discretion, or is based upon a clear error of law, or where the district court’s findings of fact are clearly erroneous. See, e.g., Massachusetts Ass’n of Older Americans v. Sharp, 700 F.2d 749, 751-52 (1st Cir.1983); Maceira v. Pagan, 649 F.2d 8, 15 (1st Cir.1981); see also General Electric Co. v. New York State Dept. of Labor, 891 F.2d 25, 26 (2d Cir.1989) (reversing denial of preliminary injunction on ERISA preemption grounds); 7 Moore, Federal Practice and Procedure ¶1 65.04[2] (2d ed. 1987). Where, as here, appellants are asking for a mandatory injunction which will change the status quo ante during the pendency of litigation, we will take into account the exigencies and circumstances of the situation. See Massachusetts Coalition of Citizens with Disabilities v. Civil Defense Agency, 649 F.2d 71, 76 n. 7 (1st Cir.1981).
To be entitled to injunctive relief a party must establish that it has a likelihood of success on the merits, that it will suffer immediate and irreparable harm if relief is not granted, that such harm outweighs any harm to the non-moving party, and that the public interest will not be adversely affected. Planned Parenthood v. Bellotti, 641 F.2d 1006, 1009 (1st Cir.1981); Lancer v. Lebanon Housing Authority, 760 F.2d 361, 362 (1st Cir.1985). The balancing of interests shifts in plaintiffs’ favor when a strong likelihood of success on the merits is shown. SEC v. World Radio Mission, Inc., 544 F.2d 535, 541-42 (1st Cir.1976).
IV. DISCUSSION
In our opinion, appellants have made a strong showing that they are likely to succeed on the merits. In so holding, we do not reach their entire array of arguments, because in our view, their main argument ultimately carries the day.
A. Preemption under the NLRA
In order to analyze preemption under the NLRA, we must first examine a bit of the Act’s evolution. Since first enacted in 1935, the NLRA “has empowered the National Labor Relations Board ‘to prevent any person from engaging in any unfair labor practice ... [defined by the Act] affecting commerce.’ ” 29 U.S.C. § 160(a). “By this language, and by the definition of ‘affecting commerce’ ... Congress meant to reach to the full extent of its power under the Commerce Clause.” Guss v. Utah Labor Relations Board, 353 U.S. 1, 3, 77 S.Ct. 598, 599, 1 L.Ed.2d 601 (1957). See also 29 U.S.C. § 152(7).7 Thus, in the area of labor relations there is “not only a general intent to pre-empt the field but also ... [the] inescapable implication of exclusiveness.” Guss, 353 U.S. at 10, 77 S.Ct. at 602. In Guss the Supreme Court went so far as to carry that principle to the point of creating a no-man’s land, in which no jurisdiction existed on behalf of state authorities to intervene in labor relations matters covered by the Act notwithstanding the Board’s refusal to exercise dominion over such disputes. It should be noted that, although Guss involved unfair labor practices, the Act uses substantially similar language regarding the representation procedures established thereunder, and there[351]*351fore the principle established by Guss is of equal application to representation matters.8
The situation created by Guss led in 1959 to the amendment by Congress of Section 14 of the Act, allowing for state intervention in labor disputes affecting commerce in which the Board has specifically declined to exercise jurisdiction.9 Prior to that amendment, as is discussed in Guss, 353 U.S. at 6-7, 77 S.Ct. at 600-01, a state could only intervene in a labor dispute affecting commerce if the Board had entered into a cession agreement pursuant to Section 10(a) of the Act,10 and then only if the state statute was consistent with a corresponding provision in the Act.
Intervention in labor matters affecting commerce today is thus limited to cession agreements by the Board with the states under Section 10(a) of the Act, or specific declinations by the Board to intervene pursuant to Section 14(c) of the Act. There is a third category, also under Section 14 of the Act,11 which allows the states to legislate to prohibit union shop agreements.
It is a textbook proposition that, under the supremacy clause of Article VI of the Constitution,12 the “supreme” congressional law supersedes or preempts state law. Preemption occurs not only when there is an outright conflict between the federal scheme and the state requirement, but also when congressional action is an implicit barrier — e.g., when state regulation interferes unduly with the accomplishment of congressional objectives. Congressional legislation in an area in which a state seeks to regulate does not necessarily preclude all state action. Nor does the fact that there is no explicit federal-state conflict or congressional statement of intent to bar state authority inescapably rule out a finding of preemption. Cf. Guss, 353 U.S. at 10, 77 S.Ct. at 602.
[352]*352The question in each case is what the purpose of Congress was [in legislating] ... Such a purpose may be evidenced in several ways. The scheme of federal regulation may be so pervasive as to make reasonable the inference that Congress left no room for the States to supplement it. Or the Act of Congress may touch a field in which the federal interest is so dominant that the federal system will be assumed to preclude enforcement of state laws on the same subject. Likewise, the object sought to be obtained by the federal law and the character of obligations imposed by it may reveal the same purpose. Or the state policy may produce a result inconsistent with the objective of the federal statute. It is often a perplexing question whether Congress has precluded state action or by the choice of selective regulatory measures has left the police power of the States undisturbed except as the state and federal regulations collide.
Rice v. Santa Fé Elevator Corp., 331 U.S. 218, 230-31, 67 S.Ct. 1146, 1152, 91 L.Ed. 1447 (1947) (citations omitted).13
The Supreme Court has recognized two types of federal preemption of state and local government action in the field of labor law. First, the Supreme Court has prohibited the states from regulating activities “which are protected by Section 7 of the National Labor Relations Act, or constitute an unfair labor practice under Section 8.” San Diego Bldg. Trades Council v. Garmon, 359 U.S. 236, 244, 79 S.Ct. 773, 779, 3 L.Ed.2d 775 (1959). Second, the Court has held that state and local governments are prohibited from regulating activities which Congress intended to be left unrestricted by any governmental power. Lodge 76, Int’l Assoc. of Machinists & Aerospace Workers v. Wisconsin Emp. Comm., 427 U.S. 132, 140, 96 S.Ct. 2548, 2553, 49 L.Ed.2d 396 (1976).14
While both forms of preemption are implicated by this appeal, we believe that the present case is most heavily influenced by the Supreme Court’s holdings in the Golden State Transit Corp. cases, which relied and expanded upon the Machinists doctrine. See Golden State Transit Corp. v. City of Los Angeles, 475 U.S. 608, 106 S.Ct. 1395, 89 L.Ed.2d 616 (1986) [Golden State I]; Golden State Transit Corp. v. City of Los Angeles, 493 U.S. 103, 110 S.Ct. 444, 107 L.Ed.2d 420 (1989) [Golden State II]. While there are differences between the Golden State cases and the present case, we think the similarities have greater salience.
In Golden State I the employer sought renewal of a taxicab operating license from the City of Los Angeles. At the time the employer was engaged in a labor dispute with the union that represented its employees. The City Council conditioned renewal of the franchise on settlement of the labor dispute by a specific date. When the strike was not settled by that date, the franchise expired. The Supreme Court ruled that the city’s action in conditioning renewal of the franchise on settlement of the labor dispute was preempted by the Act. The Court stated, in language which we believe is adaptable to the present controversy:
Although the labor-management relationship is structured by the NLRA, certain areas intentionally have been left “ ‘to be controlled by the free play of economic forces.’ ” ... States are therefore prohibited from imposing additional restrictions on economic weapons of self-help, ... unless such restrictions presumably were contemplated by Congress.... “[T]he crucial inquiry regarding pre-emption is the same: whether ‘the exercise of plenary state authority to curtail or [353]*353entirely prohibit self-help would frustrate effective implementation of the Act’s processes.’ ”
Golden State I, 475 U.S. at 614-15, 106 S.Ct. at 1398-99 (citations omitted). The city’s insistence on a settlement was preempted by the Act because it “ ‘entered into the substantive aspects of the bargaining process to an extent Congress has not countenanced.’ ” Id. at 615-16, 106 S.Ct. at 1399 (citations omitted). This was so because “[t]he NLRA requires an employer and a union to bargain in good faith, but it does not require them to reach agreement.” Id. at 616, 106 S.Ct. at 1399.
In Golden State II, where the issue involved the availability of compensatory damages, the Supreme Court reiterated with even greater firmness the NLRA’s subordination of state interests to the principle of unfettered collective bargaining. The Court declared that the Machinists rule — shielding the collective bargaining process from government interference— was not designed “to answer the question whether federal or state regulations should apply to certain conduct. Rather, it is more akin to a rule that denies either sovereign the authority to abridge a personal liberty.” Golden State II, 110 S.Ct. at 451-52 (emphasis added). The Court concluded that the Machinists preemption rule “is a guarantee of freedom for private conduct that the state may not abridge.” Id. at 452.
In the present case, the state’s intrusion into the bargaining process is pervasive. The state not only mandates that a labor agreement be reached before a bid is awarded, but dictates with whom that agreement is going to be entered, and specifies what its contents shall be. For all intents and purposes the state here eliminates the bargaining process altogether. Inasmuch as regulation of this conduct15 seems central to federal labor relations, we do not see how it could be considered peripheral under the Garmon analysis. Gar-mon, 359 U.S. at 243, 79 S.Ct. at 778. Compare Belknap, Inc. v. Hale, 463 U.S. 491, 509, 103 S.Ct. 3172, 3182, 77 L.Ed.2d 798 (1983) (third parties hired as strike replacements had state-law causes of action based on misrepresentations by the employer); Automobile Workers v. Russell, 356 U.S. 634, 635, 78 S.Ct. 932, 933, 2 L.Ed.2d 1030 (1958) (state court jurisdiction over common law tort action against union for mass picketing upheld); Youngdahl v. Rainfair, 355 U.S. 131, 132, 78 S.Ct. 206, 208, 2 L.Ed.2d 151 (1957) (same re injunc-tive power to prevent interference with free use of streets); Automobile Workers v. Wisconsin Emp. Rel. Board, 351 U.S. 266, 274, 76 S.Ct. 794, 799, 100 L.Ed. 1162 (1956) (same re power to enjoin violent union conduct); United Constr. Workers v. Laburnum Constr. Corp., 347 U.S. 656, 657, 74 S.Ct. 833, 834, 98 L.Ed. 1025 (1954) (state may exercise its historic powers over such traditionally local matters as public safety and order and the use of streets and highways); Allen-Bradley Local v. Wisconsin Emp. Rel. Board, 315 U.S. 740, 749, 62 S.Ct. 820, 825, 86 L.Ed. 1154 (1942) (same).
To be sure, there may be instances where the “regulated conduct touch[es] interests so deeply rooted in local feeling and responsibility that, in the absence of compelling congressional direction, [a court] could not infer that Congress had deprived the States of the power to act.” Garmon, 359 U.S. at 244, 79 S.Ct. at 779. The district judge, in a commendable attempt to harmonize the irreconcilable conflicts presented by this difficult case, reasoned that even if the Master Labor Agreement “were to have some impact on NLRA-regulated conduct, that impact must be considered in the light of important state interest, namely the scheduled and court-ordered completion of the harbor clean-up expeditiously and without unnecessary expense.” In effect, the court held that this public purpose sani[354]*354tized its constitutional shortfalls. While we do not totally fault the court’s efforts in this respect, nor disagree as to the importance of the Boston Harbor clean-up, it cannot be said that congressional concern for a uniform, national labor policy as embodied in the NLRA, is entitled to secondary deference. Importantly, the regulated conduct here is the labor relations/bargaining process itself. Such processes have been termed by Congress as paramount to national, not local, interests. We, ourselves, have recognized as much. See General Electric Co. v. Callahan, 294 F.2d 60, 67 (1st Cir.1961) (holding that a state labor board’s interference with a labor contract negotiation “conflict[ed] with the national policy of free and unfettered collective bargaining”), cert, dismissed, 369 U.S. 832, 82 S.Ct. 851, 7 L.Ed.2d 840 (1962). Moreover, in at least one respect, Specification 13.1 seems not to further, but rather to trample, what the Massachusetts legislature has determined to be the Commonwealth’s interest. Massachusetts has enacted a Fair Competitive Bid Law which requires that the Commonwealth obtain through open competition the lowest responsible and eligible bid for public construction projects. Mass.Gen.Laws ch. 30, § 39M, and ch. 149, §§ 44A-I. Although we do not reach the state law arguments raised by ABC, we do note that this apparent conflict undercuts the MWRA’s position that Specification 13.1 furthers peculiarly local interests.
There are few areas in which local interest can be more legitimately exercised than in protecting the public from financial hardship caused by fiscally irresponsible persons using the state highways. Yet the Supreme Court invalidated a state statute whose purpose was resolution of such a dilemma because it concluded that it conflicted with the Federal Bankruptcy Act. Pérez v. Campbell, 402 U.S. 637, 656, 91 S.Ct. 1704, 1714, 29 L.Ed.2d 233 (1971). The Court rejected the argument that the purpose of the state law, rather than its effect on the operation of federal legislation, should govern its validity. Even if the state claimed to be concerned with promotion of highway safety, such a statute could not stand if it conflicted with the federal scheme: “[Sjuch a doctrine would enable state legislatures to nullify nearly all unwanted federal legislation by simply publishing a legislative committee report articulating some state interest or policy— other than frustration of the federal objective — that would be tangentially furthered by the proposed state law.” Id. at 652, 91 S.Ct. at 1712.
Although the local concerns that led to the promulgation of Specification 13.1 — “labor harmony during [the] life ... [of] ... this critical project” — are laudable, they conflict with paramount federal law and must therefore fall. We should add that we are in any event somewhat skeptical of the pax industrial which the Master Labor Agreement utopically promotes. This peaceable kingdom may be somewhat less than attainable considering that this contract is no bar to rival, or for that matter, anti-union, activity. See 29 U.S.C. § 158(f), last proviso.
Appellees contend that, had the Master Agreement been entered into directly between the state agency and the unions, it would be unassailable, because “[t]he National Labor Relations Act leaves regulation of the labor relations of state and local government to the States.” Abood v. Detroit Bd. of Education, 431 U.S. 209, 223, 97 S.Ct. 1782, 1793, 52 L.Ed.2d 261 (1977). Of course, if the MWRA were the actual employer of the Project laborers, the NLRA would be totally inapplicable as States are excluded from the definition of “employer.” 29 U.S.C. § 152(2).16 The state’s substantial participation in the Project, however, is not enough to alter its status from regulator to employer, nor does any party seriously claim such a relationship. There are insufficient indicia of an employer/employee relationship between the MWRA and the la[355]*355borers.17 Rather, the state is in its common role of a third party purchaser. If the state employer exclusion from the NLRA were interpreted to include all situations in which a state contracted for goods or services, the exception would likely swallow the rule.18 Allowing a state to impose restrictions upon all companies from which it purchases goods or services would effectively permit it to regulate labor relations between private employers and their employees thus totally displacing the NLRA, not just in this Project, but also statewide, and, if the practice were to become generalized, nationally. Indeed, an anti-union state government could allow only non-union employers to bid on state projects, if the state-as-employer argument is taken to its extreme.
As discussed herein, a state is not included in the definition of employer. Normally, employers cannot enter into pre-hire agreements. Congress created an exception to this prohibition for employers in the construction industry, as such term is defined in the Act. To suggest, as is done by the dissent, see p. 364 (Breyer, C.J., dissenting), that a state, by definition not an employer within this statute, somehow reverts to the status of statutory employer for purposes of this exception is fancy judicial foot work at its nimblest. The facts provide a dose of reality that not only undercuts the dissent’s imaginative analysis of the legislative history of the construction industry exceptions, but also destroys its premise that the state should be treated as a private employer. Indisputably, the MWRA is not an employer under either the law, 29 U.S.C. § 152(2), or the facts of this case.
Thus, absent some principled basis for reading an exception into the legal framework, a matter which we discuss post, we believe that either because of its regulation of matters protected by § 7 of the Act {e.g., the mandatory recognition of the Trades Council), Garmon, 359 U.S. at 245, 79 S.Ct. at 779, or because of its direct intrusion into the collective bargaining process, Golden State I, 475 U.S. at 614-15, 106 S.Ct. at 1398-99, Specification 13.1 frustrates the purposes of the Act and is, therefore, preempted.
B. Sections 8(e) and (f) of the Act — The construction industry exemption
Appellees argue, and the district court in effect ruled, that the provision of Sections 8(e) and (f) of the Act validate the Master Labor Agreement “in the context of the unique conditions which exist in the construction industry.”
Section 8(e) of the Act19 makes it an unfair labor practice for an employer and a [356]*356union to enter into what is commonly referred to as a “hot cargo” agreement. Under a “hot cargo” agreement, generally, the employer binds itself not to do business with another employer or person. This type of agreement developed out of situations in which unions did not want their members to be working or handling “struck” goods. Section 8(e), however, contains a limited exemption for the construction industry, “relating to the contracting or subcontracting of work to be done at the site of the construction.” Thus “hot cargo” agreements are legal, to this circumscribed extent, in the construction industry.
Section 8(f) of the Act20 creates another exception for the building and construction industry by allowing certain actions, which would otherwise be prohibited as unfair labor practices, by employers and unions in that line of work. Thus a construction industry employer may enter into a so-called “pre-hire” agreement with a union, e.g., a collective bargaining agreement wherein the union’s representative status is immaterial and which in fact is usually entered into prior to the hiring of any employees. Furthermore, such an agreement may contain a union shop provision requiring membership in the union seven days after hiring, 29 U.S.C. § 158(f)(2), which would otherwise be illegal;21 a requirement that the employer notify the union of job openings giving the labor organization an opportunity to refer qualified job workers, 29 U.S.C. § 158(f)(3); as well as a condition establishing minimum training or experience qualifications and area-wide seniority. 29 U.S.C. § 158(f)(4).
It shall not be an unfair labor practice under subsections (a) and (b) of this section for an employer engaged primarily in the building and construction industry to make an agreement covering employees engaged (or who, upon their employment, will be engaged) in the building and construction industry with a labor organization of which building and construction employees are members (not established, maintained, or assisted by any action defined in subsection (a) of this section as an unfair labor practice) because (1) the majority status of such labor organization has not been established under the provisions of section 159 of this title prior to the making of such agreement, or (2) such agreement requires as a condition of employment, membership in such labor organization after the seventh day following the beginning of such employment or the effective date of the agreement, whichever is later, or (3) such agreement requires the employer to notify such labor organization of opportunities for employment with such employer, or gives such labor organization an opportunity to refer qualified applicants for such employment, or (4) such agreement specifies minimum training or experience qualifications for employment or provides for priority in opportunities for employment based upon length of service with such employer, in the industry or in the particular geographical area: Provided, That nothing in this subsection shall set aside the final proviso to subsection (a)(3) of this section: Provided further, That any agreement which would be invalid, but for clause (1) of this subsection, shall not be a bar to a petition filed pursuant to section 159(c) or 159(e) of this title.
A construction industry labor contract entered into under the exceptional provisions of Section 8(f) is not, as specifically stated in the final proviso of that section, a bar to a petition for election, be it by a rival union,22 by the employer23 or by the employees themselves.24 If the employees elect a rival union as their bargaining agent, neither the winning union nor the employer are required to assume the 8(f) contract. If the employees reject the 8(f) contracting union as their bargaining agent and do not choose another bargaining agent, the contract is totally void because one of the contracting parties is disqualified.
It is apparent from the above that under the exceptions established by Sections 8(e) and (f) of the Act, the Master Labor Agreement between the Trades Council and Kaiser is a valid labor contract. See Jim McNeff, Inc. v. Todd, 461 U.S. 260, 265-66, 103 S.Ct. 1753, 1756, 75 L.Ed.2d 830 (1983).
[357]*357That conclusion, however, is irrelevant to the preemption issue at hand. Appellants do not challenge the validity of that agreement; they contest the legality of Specification 13.1, which establishes recognition of the Trades Council and signing of the Master Labor Agreement as a condition of the award of an MWRA bid. On said issue, Sections 8(e) and (f) have no bearing, except as reinforcement for appellants’ preemption arguments. It is clear, both from their nature and history, that Congress extensively debated and considered these controversial provisions before their enactment. See generally, 1959 U.S.Code Cong. & Admin.News, p. 2318 et seq. It is unlikely that Congress intended to leave open to Balkanization by the states such core areas as unfair labor practices and collective bargaining, which are the matters inescapably arising from Sections 8(e) and (f) problems. Indeed, nowhere in the legislative history is there any indication that a state would be allowed to impose this type of regulation. The history of Sections 8(e) and (f) discusses private employers only; the silence as to permitted state regulation is deafening. In enacting these exceptional provisions, Congress occupied the field to the exclusion of such local regulations as are exemplified by Specification 13.1. See Guss, 353 U.S. at 10, 77 S.Ct. at 602. Although the Master Labor Agreement is a valid contract pursuant to Sections 8(e) and (f) of the Act, Specification 13.1 unduly interferes with the area of labor negotiations which Congress clearly intended to leave unregulated under the same statute: the collective bargaining process. See Golden State I, 475 U.S. at 614-16, 106 S.Ct. at 1398-99.
C. Proprietary or regulatory interest
In Wisconsin Dept. of Indus. v. Gould, 475 U.S. 282, 106 S.Ct. 1057, 89 L.Ed.2d 223 (1986), the Court struck down a state statute barring repeat violators of the NLRA from bidding on state contracts as preempted under the Garmon doctrine. Gould, 475 U.S. at 291, 106 S.Ct. at 1063. The state argued that it should not be restricted by the Commerce Clause when it acts as a market participant. The Court rejected this argument, noting first, that the state was functioning more as a regulator than as a market participant, and second, that the exception to the Commerce Clause might be broader than state action allowed under the NLRA. Id. at 289-90, 106 S.Ct. at 1062-63. The Court based its analysis on the differing purposes served by the Commerce Clause and the NLRA: whereas the Commerce Clause contains “ ‘no indication of a constitutional plan to limit the ability of the States themselves to operate in the free market,’ ... [t]he NLRA, in contrast, was designed in large part to ‘entrust administration of the labor policy for the Nation to a centralized administrative agency.’ ” Id. (citations omitted).
In concluding the Gould opinion, the Court explored, but did not define, the boundaries of its holding:
We do not say that state purchasing decisions may never be influenced by labor considerations, any more than the NLRA prevents state regulatory power from ever touching on matters of industrial relations. Doubtless some state spending policies, like some exercises of the police power, address conduct that is of such “peripheral concern” to the NLRA, or that implicates “interests so deeply rooted in local feeling and responsibility,” that pre-emption should not be inferred. Garmon, 359 U.S. at 243-44 [79 S.Ct. at 778]; see also, e.g., Belknap, Inc. v. Hale, 463 U.S. 491, 498 [103 S.Ct.3172, 3177, 77 L.Ed.2d 798] (1983). And some spending determinations that bear on labor relations were intentionally left to the States by Congress. See New York Tel. Co. v. New York State Labor Dept., 440 U.S. 519 [99 S.Ct. 1328, 59 L.Ed.2d 553] (1979).
Gould, 475 U.S. at 291, 106 S.Ct. at 1063. Having opened this door, however, the Court firmly closed it on the Wisconsin rule at issue, stating that “[w]e are not faced here with a statute that can even plausibly be defended as a legitimate response to state procurement constraints or to local economic needs, or with a law that pursues a task Congress intended to leave to the States.” Id.
[358]*358Appellees submit that this language creates an exception to the preemption doctrine arising out of the distinction between a state’s interest as proprietor versus its interest as regulator. Where a spending decision such as Specification 13.1 is animated by the exigency of doing business rather than the regulation of labor relations; where the measure's effect on labor relations is incidental to a legitimate and necessary proprietary purpose; that measure, argue appellees, is saved from preemption by the supposed Gould exception. As a subsidiary proposition, appellees also contend that the MWRA’s action would be lawful under Sections 8(e) and (f) were it undertaken by a private employer, and that there is no basis under the NLRA to treat a state more harshly than a comparably situated private party.
We can dispose of the latter contention quite briefly before moving to the more troublesome principal point. First, Congress is perfectly capable of distinguishing between states and private parties when it chooses, and it has so chosen here. Sections 8(e) and (f) refer to “employers.” The Act states that the term “employer” “shall not include ... any State or political subdivision thereof.” 29 U.S.C. § 152(2). Thus it is clear that the MWRA is not encompassed by Sections 8(e) and (f), and its conduct cannot be compared with what might be acceptable conduct by a private employer.25
Moreover, the Court itself has underscored the state/private distinction, in the very ease appellees use to support their proprietary interest argument. The Gould opinion states:
[Government occupies a unique position of power in our society, and its conduct, regardless of form, is rightly subject to special restraints. Outside the area of Commerce Clause jurisprudence, it is far from unusual for federal law to prohibit States from making spending decisions in ways that are permissible for private parties. The NLRA, moreover, has long been understood to protect a range of conduct against state but not private interference. The Act treats state action differently from private action not merely because they frequently take different forms, but also because in our system States simply are different from private parties and have a different role to play.
Gould, 475 U.S. at 290, 106 S.Ct. at 1063. Thus it is plain that the private employer comparison merits little weight. The MWRA is an arm of the state, and its actions must be judged accordingly.26
Moving to the issue of proprietary interest, we find that we are ultimately unpersuaded that such an exception, if it exists at all, applies in this case. Other than the dicta in Gould, the Supreme Court has never articulated — much less applied — a proprietary interest exception. Moreover, the cases cited in Gould do not support an exception for the situation at hand. Belknap v. Hale, 463 U.S. at 509, 103 S.Ct. at 3182, is one of a line of eases permitting state tort law remedies to coexist with the NLRA. See supra at p. 353. These cases merely indicate application of the Garmon analysis allowing state action in “peripheral” areas. Garmon, 359 U.S. at 243, 79 S.Ct. at 778. For an example of a “spending determination” addressing “state procurement constraints” or “local economic need,” Gould, 475 U.S. at 291, 106 S.Ct. at 1063, the Court cited New York Tel. Co. v. New York State Labor Dept., 440 U.S. 519, 99 S.Ct. 1328, 59 L.Ed.2d 553 (1979). In that case, the Court found no preemption where the state sought to impose a mandatory minimum benefit (unemployment compensation) [359]*359through a law of general applicability. Id. at 545-46, 99 S.Ct. at 1343-44.27 See also Fort Halifax v. Coyne, 482 U.S. 1, 22, 107 S.Ct. 2211, 2223, 96 L.Ed.2d 1 (1987) (upholding Maine statute requiring employers to provide severance pay); Metropolitan Life Ins. Co. v. Massachusetts, 471 U.S. 724, 755, 105 S.Ct. 2380, 2397, 85 L.Ed.2d 728 (1985) (upholding state statute requiring certain minimum health benefits to be included in employee health plans). As this court has noted, because such a statute “ ‘neither encourages nor discourages the collective bargaining processes that are the subject of the NLRA,’ it is ‘a valid and unexceptional exercise of the State’s police power.’ ” Beckwith v. United Parcel Service, Inc., 889 F.2d 344, 349 (1st Cir.1989) (quoting Metropolitan Life Ins., 471 U.S. at 755, 758, 105 S.Ct. at 2397, 2398). Plainly, the same cannot be said of Specification 13.1, which mandates adherence to a particular contract with a particular group of labor unions, in lieu of the collective bargaining process.
Our reading of the Gould “exception” is that it largely restates the Garmon proposition: Some state interference into the collective bargaining process is permitted if it, first, is “peripheral” to federal labor policy, or, second, pertains to matters “deeply rooted in local feeling and responsibility.” Garmon, 359 U.S. at 243-44, 79 S.Ct. at 778-79. As we have stated ante, at p. 353, Specification 13.1 is a direct regulation of the collective bargaining process. Thus it can neither be termed “peripheral” nor “local.” To be sure, the Boston Harbor clean-up is a matter of great local interest. It is not the clean-up, however, which is being regulated; collective bargaining is being regulated, and that cannot be.
At any rate, Garmon is only one avenue of preemption under federal labor law — albeit one which most likely applies to Specification 13.1. This opinion, however, has rested largely on the Machinists doctrine as articulated in Golden State I. It is noteworthy that in Golden State I, once the Court had determined that the City of Los Angeles had directly interfered with the collective bargaining process, it expressly declined to consider the nature and extent of the City’s interest in resolving the labor dispute. Golden State I, 475 U.S. at 617-18 and n. 8, 106 S.Ct. at 1400 and n. 8.28 Yet the City would seem to have had a strong and legitimate interest in ensuring the adequacy of its transportation system, see id. at 620, 106 S.Ct. at 1401 (Rehnquist, J., dissenting) — at least tantamount to the MWRA’s interest in ensuring speedy completion of the harbor clean-up. We can only conclude that the lesson of the Golden State cases is that, where interference into the collective bargaining process by the state is direct, an asserted state interest of the type at issue here, whether “proprietary” or otherwise, cannot justify the interference.
D. Other Allegations
In view of our ruling on the issue of preemption of Specification 13.1 by the Act, it is unnecessary for us to reach the other questions raised by the appeal. See Lane [360]*360v. First National Bank of Boston, 871 F.2d 166, 168 (1st Cir.1989).
V. CONCLUSION
Specification 13.1 unduly restricts aspects of the labor-management relationship intentionally left unregulated by Congress and is thus preempted by the National Labor Relations Act, as amended, 29 U.S.C. § 151, et seq. The decision of the district court is reversed. The district court, at the direction of this court in its original panel opinion in this case, has already issued a preliminary injunction against enforcement of Specification 13.1. That injunction remained in force during the pendency of the rehearing en banc. Therefore, we simply order that the preliminary injunction continue in effect during the further proceedings in this case.
Reversed and remanded. Costs to appellants.