Opinion for the Court filed by Circuit Judge GARLAND.
Concurring opinion filed by Senior Circuit Judge SILBERMAN.
GARLAND, Circuit Judge.
Joseph B. Simpson, a citizen of Jamaica, pled guilty to re-entering the United States unlawfully after having been deported following conviction for -an aggravated felony. Due to uncertainty regarding the continued validity of the United States Sentencing Guidelines in the months after the Supreme Court decided Blakely v. Washington, 542 U.S. 296, 124 S.Ct. 2531, 159 L.Ed.2d 403 (2004), the district court imposed a 46-month prison term under two separate rationales. The court first sentenced Simpson by applying the Guidelines as mandatory; it then sentenced him as it would in its discretion, treating the Guidelines as advisory only. Simpson now appeals, seeking a remand to the district court for re-sentencing in light of the 'Supreme Court’s decision in United States v. Booker, 543 U.S. 220, 125 S.Ct. 738, 160 L.Ed.2d 621 (2005). We conclude that the alternative sentencing methodology employed by the district court was consistent with the Supreme Court’s subsequent decision in Booker and that Simpson’s sentence must therefore be affirmed.
I
On October 6, 2000, Simpson was convicted in federal court in Virginia of conspiring to possess with intent to distribute 100 kilograms or more of marijuana. As a result of that conviction, Simpson was deported from the United States on October 23, 2003. See 8 U.S.C. § 1227(a) (2) (A) (i) (II). Two months later, using a false name, Simpson re-entered the United States near Port Everglades, Florida. One month after re-entering the country, Simpson was arrested in the District of Columbia for threatening to kill his wife with a kitchen knife. Fingerprints and photographs revealed Simpson’s true identity, and on February 27, 2004, he was [1180]*1180indicted on one count of re-entry by an alien, deported following convictiop for an aggravated felony, in violation of 8 U.S.C. § 1326(a), (b)(2).
Simpson signed an agreement to plead guilty to the indictment. The parties agreed that Simpson’s base offense level under the Sentencing Guidelines was 8, and that his offense level should be enhanced to 24 “because the defendant ,was previously deported after a conviction for a drug trafficking offense for which the sentence imposed was greater than 13 months.” Plea Agreement 2; see U.S.S.G. § 2L1.2(b)(l)(A). The parties further agreed that the offense level should be reduced by 3 levels to 21, due to Simpson’s acceptance of responsibility. See U.S.S.G. § 3E1.1. The plea agreement did not include a stipulation regarding Simpson’s criminal history category. The district court accepted the plea at a hearing on June 10, 2004, and it scheduled sentencing for August 25.1
Following entry of the plea, the U.S. Probation Office prepared a Presentence Report (PSR) that accepted the parties’ calculation of Simpson’s offense level. The PSR also placed Simpson in criminal history category III. That calculation was based on the PSR’s finding of a total of 5 criminal history points: 3 points for Simpson’s marijuana conspiracy conviction and sentence, see U.S.S.G. § 4Al.l(a), and 2 additional points for committing the re-entry offense while still under sentence (supervised release) for the marijuana conviction, see id. § 4Al.l(d). At the subsequent sentencing hearing, the district court agreed with the PSR’s offense level calculation, but added another criminal history point because the re-entry offense was committed less than two years after Simpson’s release from imprisonment. See id. § 4Al.l(e).2 The resulting 6 criminal history points did not change Simpson’s criminal history category, which remained at III. See U.S.S.G. Ch. 5, Pt. A. The combination of offense level 21 and criminal history category III yielded a Guidelines sentencing range of 46-57 months’ imprisonment. See id.
In the interim between Simpson’s plea and sentencing, the Supreme Court decided the Blakely case, in which it invalidated a Washington state determinate sentencing regime similar to the U.S. Sentencing Guidelines. The Court held that a sentencing court violates the Sixth Amendment when it imposes a sentence higher than the statutory maximum sentence it “may impose solely on the basis of the facts reflected in the jury verdict or admitted by the defendant.” Blakely, 542 U.S. at 303, 124 S.Ct. 2531. Relying on Blakely, Simpson’s counsel challenged the calculation of her client’s criminal history category as a violation of the Sixth Amendment, arguing that the category had been assigned on the basis of facts Simpson had not admitted. Def.’s Objections to PSR 2. In particular, she argued that, even if Simpson had admitted the facts necessary to assign him 3 points for the marijuana conspiracy conviction, those [1181]*11813 points would only put him in category II, which would yield a lower sentencing range (41-51 months). See Appellant’s Br. 4. The calculation that raised the criminal history category to III, she contended, required the court to find additional facts — that Simpson was on supervised release at the time of his unlawful re-entry and/or that he had committed that offense less than two years after release from imprisonment. Simpson’s counsel asserted that he had not admitted those facts, and that Blakely therefore barred the court from using them to sentence him.3 Accordingly, she asked the sentencing judge to “just use your discretion.” Sentencing Hr’g Tr. 8 (August 25, 2004).
At the August 25 sentencing hearing, the district court advised the parties that, in light of Blakely, it would give Simpson “alternative sentences”: one as if the Guidelines were “controlling,” and one as if the Guidelines were “not controlling” but could be looked to “for whatever assistance ... [the court] might be able to get from them.” Id. at 25. With respect to the latter, the court invited the parties to give it “the assistance that you would like to give ... with respect to what sentence should be imposed.” Id. at 26. Simpson’s counsel objected that the court should not announce an alternative sentence that would be “automatically imposed” if the Court of Appeals were to determine that the Guidelines sentence was unconstitutional, because “it doesn’t give the defendant a chance to respond to whatever it is the Court says was wrong with the first sentence.” Id. at 27. Counsel then went on to cite circumstances that she thought justified sentencing Simpson “at the lowest level of whatever guideline range, should the court impose a guideline range, or if the Court views the guidelines only as guidelines and not mandatory, ... [to] a sentence less than what the guidelines would otherwise dictate.” Id.
The district court proceeded to sentence Simpson under each of the two approaches. Turning first to the Guidelines, the court set forth the calculations outlined above, concluding that Simpson’s offense level was 21, that his criminal history category was III, and that the resulting Guidelines sentencing range was 46-57 months. The court then sentenced Simpson to the bottom of that range, imposing a sentence of 46 months’ imprisonment, followed by two years of supervised release. Id. at 46-48.
The court next addressed the appropriate sentence in the event the Guidelines were not controlling:
I would take into account and do take into account the seriousness of this offense, that it was a conscious, intentional decision by the defendant follovfing a conviction for an aggravated felony offense and deportation from the United States and that the Court is not confident that Mr. Simpson would not choose to return to the United States illegally in the future as well, and that the guidelines, using them only as a reference point, would suggest that an appropriate sentence for this offense should be in the range of 46 to 57 months based on a particular criminal history category.
I find in my discretion, without the guidelines, that the appropriate sentence would, be at 46 months, that that is a sentence that addresses the interests of [1182]*1182the criminal justice system and addresses the interests and sentencing objectives of punishment and deterrence and is the sentence that the Court imposes in its discretion, given all the facts and circumstances relevant here.
Id. at 49.
Simpson noted an appeal on September 2, 2004. On January 12, 2005, the Supreme Court issued its opinion in United States v. Booker, which held that Blakely applied to the U.S. Sentencing Guidelines and that the mandatory imposition of enhanced sentences under the Guidelines violated the Sixth Amendment. 125 S.Ct. at 746. In light of this holding, the Court invalidated two statutory provisions that had the effect of making the Guidelines mandatory. Id. We now consider Simpson’s appeal in the wake of Booker.
II
We begin with a discussion of Booker and of the legal doctrines governing appellate review of sentencing error. That discussion will guide the analysis in the balance of this opinion.
A
The Supreme Court’s decision in Booker consisted of two separate majority opinions. In the first, “substantive” opinion, the Court held that the Sixth Amendment is violated when a court imposes a sentence under the Sentencing Guidelines based on its own determination of “[a]ny fact (other than a prior conviction) which is necessary to support a sentence exceeding the maximum authorized by the facts established by a plea of guilty or a jury verdict ....” Booker, 125 S.Ct. at 756. The Court emphasized, however, that its conclusion “rests on the premise ... that the relevant sentencing rules are mandatory and impose binding requirements on all sentencing judges.” Id. at 749-50. “If the Guidelines as currently written could be read as merely advisory provisions that recommended, rather than required, the selection of particular sentences in response to differing sets of facts,” the Court said, “their use would not implicate the Sixth Amendment” regardless of whether they enhanced a sentence above that consistent with a plea or verdict. Id. at 750.
In the second, “remedial” opinion, the Court found that the federal statutory provisions making the Guidelines mandatory were “incompatible with [Booker’s] constitutional holding” and had to be “severed and excised.” Id. at 756. “So modified,” thé Court said, “the Federal Sentencing Act ... makes the Guidelines effectively advisory.” Id. at 757. The modified statute, the Court explained, “requires the sentencing court to consider Guidelines ranges, see 18 U.S.C.A. § 3553(a)(4)(Supp.2004), but it permits the court to tailor the sentencing in light of other statutory concerns as well, see § 3553(a) (Supp.2004).” Id.
The Booker decision resolved two companion cases, one involving defendant Freddie Booker and another involving defendant Ducan Fanfan. The two dispositions identified two kinds of sentencing error. With respect to the sentence of Freddie Booker, the Court found constitutional error under the Sixth Amendment because, in obeying the mandatory Guidelines regime, the judge had increased Booker’s sentence beyond the maximum that could have been imposed based solely [1183]*1183on the facts reflected in the jury verdict. Id. at 769.5 By contrast, the Court found no constitutional violation in defendant Du-can Fanfan’s sentence — which was the maximum Guidelines sentence authorized by the jury’s verdict without additional findings of fact. Id. at 769.6 Nonetheless, the Court vacated Fanfan’s sentence and remanded to permit either party to seek resentencing “under the system set forth” in the Booker opinions, because the district court had committed non-constitutional error by applying the Guidelines in a mandatory rather than advisory fashion. Id.
The Supreme Court’s conclusion that the sentencing courts in the companion cases had erred followed from the Court’s ruling that it “must apply today’s holdings — both the Sixth Amendment holding and our remedial interpretation of the Sentencing Act — to all cases on direct review.” Id. at 769; see also Griffith v. Kentucky, 479 U.S. 314, 328, 107 S.Ct. 708, 93 L.Ed.2d 649 (1987) (holding that a “new rule for the conduct of criminal prosecutions is to be applied retroactively to all cases ... pending on direct review ..., with no exception for cases in which the new rule constitutes a ‘clear break’ with the past”). As a consequence, on direct review appellate courts must regard any sentencing methodology that was materially inconsistent with the Booker remedial opinion — and not just the mandatory application of the Guidelines— as Booker error. A district court’s failure to consider the sentencing factors listed in 18 U.S.C. § 3553(a), for example, is a species of such non-constitutional (statutory) error. See United States v. Crosby, 397 F.3d 103, 115 (2d Cir.2005); infra Part III.B.
B
When a defendant does not timely object to an error in the district court, appellate review is limited by the “plain error” standard: “[Tjhere must be (1) error, (2) that is plain, and (3) that affect[s] substantial rights. If all three conditions are met, an appellate court may then exercise its discretion to notice a forfeited error, but only if (4) the error seriously affect[s] the fairness, integrity, or public reputation of judicial proceedings.” Johnson v. United States, 520 U.S. 461, 467, 117 5.Ct. 1544, 137 L.Ed.2d 718 (1997) (internal citations and quotation marks omitted); see also Fed. R. CRiM. P. 52(b). Under the plain error standard, it “is the defendant rather than the Government who bears the burden of persuasion with respect to prejudice.” United States v. Olano, 507 U.S. 725, 734, 113 S.Ct. 1770, 123 L.Ed.2d 508 (1993).
If a defendant does timely object to an alleged error in the district court, appellate review is instead conducted in accordance with the “harmless error” standard: If the district court erred, we must correct the error if it affects the defendant’s “substantial rights.” See Fed. R. CRiM. P. 52(a). “[I]n most cases[, this] means that the error must have been prejudicial: It must have affected the outcome of the district court proceedings.” Olano, [1184]*1184507 U.S. at 734, 113 S.Ct. 1770. The government bears the burden- of proving that prejudice did not result from the error. See id.
The test for harmless error comes in two models, one for non-constitutional error and one for error of constitutional dimension. See United States v. Powell, 334 F.3d 42, 45 (D.C.Cir.2003). A constitutional error is harmless - if it appears “beyond a reasonable doubt that the error complained of did not contribute to the [sentence] obtained.” Chapman v. California, 386 U.S. 18, 24, 87 S.Ct. 824, 17 L.Ed.2d 705 (1967). By contrast, a non-constitutional error is harmless if it did not have a “substantial and injurious effect or influence in determining” the sentence. Kotteakos v. United States, 328 U.S. 750, 776, 66 S.Ct. 1239, 90 L.Ed. 1557 (1946).
Ill
Simpson contends that the district court committed constitutional Booker error by increasing his statutory maximum based on the court’s own findings of fact under a mandatory guidelines system. Further, because his trial counsel timely objected on that ground, Simpson contends that his sentence may be affirmed only if the error was harmless. Finally, insisting that the error was not harmless, Simpson argues that his sentence should be vacated and his case remanded for resentencing.
The threshold question is whether there was error at all. Although the district court spoke of imposing two “sentences,” a primary and an alternative, the “judgment in a criminal case” filed by that court records only a single sentence: 46 months’ imprisonment. J.Á. 28-29. The judgment states that the sentence “is imposed pursuant to the Sentencing Reform Act of 1984” and that, “[ajlternatively, the same sentence is imposed by the Court in its discretion assuming the Sentencing Guidelines do not apply.” Id. at 28 (emphasis added).7
There is no question that the court’s first rationale (and “sentence”) was error under Booker, as it was calculated based on a mandatory application of the Guidelines.8 But “[i]n cases on appeal from the district court, we are to review ‘judgments, not opinions.’ ” People’s Mojahedin Org. of Iran v. U.S. Dep’t of State, 182 F.3d 17, 23 n. 7 (D.C.Cir.1999) (quoting Chevron U.S.A. Inc. v. Natural Resources Def. Council, 467 U.S. 837, 842, 104 S.Ct. 2778, 81 L.Ed.2d 694 (1984)); see Black v. Cutter Laboratories, 351 U.S. 292, 297, 76 S.Ct. 824, 100 L.Ed. 1188 (1956). Of course, a sentence based on an invalid rationale may be erroneous. But here, the [1185]*1185district court provided two independent rationales for the same sentence of 46 months. If the alternative rationale is sufficient to support that judgment, the judgment must be upheld. See, e.g., United States v. Jones, 948 F.2d 732, 740-41 (D.C.Cir.1991) (affirming a Guidelines departure that rested on both permissible and impermissible grounds); United States v. Bowie, 232 F.3d 923, 929 (D.C.Cir.2000) (upholding a district court’s evidentiary ruling on that court’s alternative ground); United States v. Lugg, 892 F.2d 101, 105 (D.C.Cir.1989) (denial of rehearing en banc) (finding no error in a decision due to a valid independent ground).
On first glance, it does not appear that there was a material error in the alternative rationale relied on by the district court. In United States v. Coles, 403 F.3d 764 (D.C.Cir.2005), a plain error case, we said that “[a] prescient pre-Booker sentencing court committing no error would have behaved just as a sentencing court in the post -Booker era will operate: it would have treated the Guidelines as advisory.” Id. at 768 (emphasis added). The district court here looks very much like that hypothetically prescient court. It considered the Guidelines as a “reference point,” Sentencing Hr’g Tr. 49, and cited a number of other factors relevant under § 3553(a) as well, see id. In the balance of this Part, we consider three specific errors that Simpson nonetheless contends are reflected in the district court’s alternative rationale.
Simpson’s first contention is that the court’s imposition of an alternative sentence violated “the long-standing judicial canon prohibiting advisory opinions.” Appellant’s Br. 8. At oral argument, Simpson conceded that this was not a reference to “advisory opinions” in the Article III sense, since there was — and continues to be — a live dispute between the parties that the federal courts must adjudicate. Cf. Flast v. Cohen, 392 U.S. 83, 95-97, 88 S.Ct. 1942, 20 L.Ed.2d 947 (1968) (noting that the proscription against advisory opinions is based on Article Ill’s limitation of the federal judicial power to “Cases” and “Controversies”). Rather, he contends that the announcement of an alternative sentence violates prudential norms.
We disagree. As discussed above, Simpson’s alternative sentence was essentially an independent ground by which the district court reached the same judgment — a sentence of 46 months’ imprisonment — and thereby hoped to avoid the need for resentencing if the constitutional challenge came out as the court expected it would. The provision of alternative rationales for the same judgment does not violate prudential norms; to the contrary, it is a common component of judicial opinions.9 We find no error in the district court’s decision merely to announce an alternative sentence.
Simpson’s second contention is that Booker’s remedial opinion requires [1186]*1186courts to base sentences on the factors listed in 18 U.S.C. § 3553(a), and that the district court did not do so here.. Section 3553(a) enumerates a number of factors that a court “shall” consider in imposing a sentence. These include the (now advisory) range established by the Guidelines. See 18 U.S.C. § 3553(a)(4). But they also include such factors as “the nature and circumstances of the offense and the history and characteristics of the defendant,” id. § 3553(a)(1); the need for the sentence to -“reflect the seriousness of the offense,” to “promote respect for the law,” to “provide just punishment,” to “afford adequate deterrence,” to “protect the public,” and to “provide the defendant with needed, ... training [and] medical care,” id. § 3553(a)(2); and the need to “avoid unwarranted sentence disparities” among similarly situated defendants, id. § 3553(a)(6).
Simpson is correct that Booker required sentencing courts to consider the § 3553(a) factors. 125 S.Ct. at 764 (“Without the ‘mandatory’ provision, the [Federal Sentencing] Act nonetheless requires judges to take account of the Guidelines together with [the] other sentencing goals. See 18 U.S.C.A. § 3553(a) (Supp.2004).”). In so doing, however, the Supreme Court did not create a wholly new obligation. As Simpson acknowledges, see Appellant’s Br. 19, judges have been required to consider the § 3553(a) factors “in determining the particular sentence to be imposed,” 18 U.S.C. § 3553(a), since the enactment of the Sentencing Reform Act of 1984. See 18 U.S.C. § 3582; see also Koon v. United States, 518 U.S. 81, 108, 116 S.Ct. 2035, 135 L.Ed.2d 392 (1996) (“The statute requires a court to consider the listed goals .... in determining which sentence to choose from a given Guideline range or from outside the range, if a departure is appropriate.”).
The district court made clear that it did consider those factors. In explaining its alternative sentence, the court expressly addressed the nature and circumstances of the offense and the history and characteristics of the defendant:
[I take] into account the seriousness of this offense, that it was a conscious, intentional decision by the defendant following a conviction for an aggravated felony offense and deportation ... and that the Court is not confident that Mr. Simpson would not choose to return to the United States illegally in the future as well.
Sentencing Hr’g Tr. 49. The court also took into account “the interests of the criminal justice system” and “the interests and sentencing objectives of punishment and deterrence.” Id. All of this sounds in the terms of § 3553(a), and the court’s references manifest an understanding of its statutory responsibility. See United States v. Solis-Vaquera, 147 Fed.Appx. 608 (7th Cir.2005) (inferring that a sentencing court had examined the § 3553(a) factors from the fact that it referenced three of them, albeit without statutory citation).
It is true that the district court did not specifically refer to each factor listed in § 3553(a). But we have not required courts to do so. See United States v. Ayers, 428 F.3d 312, 315 (D.C.Cir.2005) (“[W]e ordinarily presume a district court imposing an alternative non-guidelines sentence took into account all the factors listed in § 3553(a) and accorded them the appropriate significance.”). Nor have other circuits. See United States v. Robles, 408 F.3d 1324, 1328 (11th Cir.2005); cf. Crosby, 397 F.3d at 112-13 (noting that the Second Circuit’s previous decisions involving “a sentencing judge’s duty to ‘consider’ matters relevant to sentencing .... have refrained from imposing any rigorous re[1187]*1187quirement of specific articulation by the sentencing judge”). Section 3553(c) provides that “[t]he court, at the time of sentencing, shall state in open court the reasons for its imposition of the particular sentence.” 18 U.S.C. § 3553(c). The district court met that requirement here, and the statute does not require more in the way of explanation. See United States v. Bridges, 175 F.3d 1062, 1066 (D.C.Cir. 1999); United States v. Dozier, 162 F.3d 120, 124-25 (D.C.Cir.1998).10 When a defendant has not asserted the import of a particular § 3553(a) factor, nothing in the statute requires the court to explain sua sponte why it did not find that factor relevant to its discretionary decision. And nothing in Booker added such a requirement. See Robles, 408 F.3d at 1328 (“Even [post-Booker ], we would not expect the district court in every case to conduct an accounting of every § 3553(a) factor ... and expound upon how each factor played a role in its sentencing decision.”); see also United States v. Dean, 414 F.3d 725, 728 (7th Cir.2005) (rejecting the contention that “it is the duty of the sentencing judge, in every case and whether or not the defendant invokes any of the factors mentioned in section 3553(a), to make an explicit, articulated analysis of all of them a part of the sentencing process”); United States v. George, 403 F.3d 470, 472-73 (7th Cir.2005) (“Judges need not rehearse on the record all of the considerations that 18 U.S.C. § 3553(a) lists; it is enough to calculate the range accurately and explain why (if the sentence lies outside it) this defendant deserves more or less.”).11
C
Simpson’s third contention is that, by concomitantly imposing primary and alternative sentences, the district court violated his “right to be present at his sentencing and to have an opportunity to present argument under now-applicable law.” Appellant’s Br. 7-8. The first half of this contention need not detain us, since Simpson was present at the sentencing hearing at which his (single) 46-month term was imposed. The real question is posed by the second half of the contention: Did Simpson have an opportunity at that hearing to present argument consistent with the law Booker later set down?
Simpson contends that he did not have such an opportunity because there were a variety of mitigating circumstances that courts were not permitted to consider — or [1188]*1188to consider fully — under the mandatory Guidelines regime that preceded Booker. Simpson’s opening brief contains a single such example. He argues that, due to his status as a deportable alien, he faces “a fortuitous increase in the severity of his sentence” — by which he means that he is ineligible for early release to community confinement or assignment to a minimum security prison. Appellant’s Br. 20. And Simpson notes that, pr e-Booker, some courts had held that downward departures from the Guidelines sentencing range on the ground of such ineligibility were not available in unlawful re-entry cases. See, e.g., United States v. Ebolum, 72 F.3d 35, 38-39 (6th Cir.1995).
In his reply brief, Simpson cites a second mitigating circumstance that he contends he was likewise unable to advance pr e-Booker. He argues that, as an unlawful re-entrant arrested in the District of Columbia, he faces a stiffer sentence than similar re-entrants arrested in border jurisdictions with “fast-track” departure programs. See United States v. Banuelos-Rodriguez, 215 F.3d 969, 971 (9th Cir. 2000) (noting that, under the fast-track program in one California district, most unlawful re-entrants are permitted to plead to an offense that carries a two-year statutory maximum sentence). In light of § 3553(a)(6), Simpson contends, he should have been able to ask the court to reduce his sentence, to avoid that disparity. See 18 U.S.C. § 3553(a)(6) (requiring the sentencing court to consider “the need to avoid unwarranted sentence disparities among defendants with similar records who have been found guilty of similar conduct”).
The flaw in Simpson’s general argument is that, although consideration of some mitigating factors was indeed barred (or limited) under the mandatory Guidelines regime, see Koon, 518 U.S. at 92-95, 116 S.Ct. 2035, the alternative sentencing methodology employed by his sentencing court did not treat the Guidelines as mandatory. Nor did the court exclude or limit its consideration of any category of sentencing factors. To the contrary, the court extended Simpson an open-ended invitation to make mitigating arguments, regardless of whether they would have been available under the Guidelines scheme. See Sentencing Hr’g Tr. 25-26. And Simpson responded to that invitation by citing a series of factors in support of a sentence well below the Guidelines range. See Sentencing Hr’g Tr. 27-34.12 Accordingly, and contrary to his contention on appeal, Simpson did have an opportunity at his sentencing hearing to present argument consistent with the law as later set forth in Booker.
It is true that the district court did not address the two specific mitigating circumstances Simpson cites in his appellate briefs. That was not, however, because the court barred their consideration. Rather, it was because Simpson failed to suggest them. In the closest analogy under the mandatory Guidelines regime, this Circuit initially ruled that it could not discern error at all in a court’s failure to address unrequested grounds for a discretionary sentencing departure. See United States [1189]*1189v. Leandre, 132 F.3d 796, 808 (D.C.Cir. 1998) (holding that “the district court cannot be faulted for failing sua sponte to also address whether [the defendant’s] deporta-ble status would affect the severity of his sentence”); see also United States v. Pinnick, 47 F.3d 434, 440 (D.C.Cir.1995). In later cases, we settled on a plain error standard of review for such claims. See United States v. Draffin, 286 F.3d 606, 609 (D.C.Cir.2002) (holding that the failure to grant a sentencing departure on an unrequested ground is reviewable only for plain error); In re Sealed Case, 204 F.3d 1170, 1173 (D.C.Cir.2000) (same).
We cannot find plain error here. To establish the second element of plain error, see supra Part II.B, an appellant must show that, “from the perspective of the trial court, the claimed error was so plain that the trial judge and prosecutor were derelict in countenancing it, even absent the defendant’s timely assistance in detecting it.” Draffin, 286 F.3d at 610 (internal quotation marks omitted). Given the multitude of factors potentially relevant in a discretionary sentencing scheme, we must be particularly cautious in finding plain error when trial counsel has failed to suggest a particular factor, lest we end up remanding whenever appellate counsel asserts a factor her predecessor did not. Indeed, under the prior sentencing regime, we held that “[o]rdinarily, [plain] error will not be found where the lawyer fails to propose a discretionary departure ground .... ” Draffin, 286 F.3d at 610; see also Leandre, 132 F.3d at 808. Moreover, given the district court’s adoption of an alternative sentencing methodology under which it was willing to consider any mitigating circumstances, Simpson cannot satisfy his burden of proving (under the third element of the plain error test) that, if only the court had had the benefit of reading Booker itself, there is a reasonable likelihood it would have considered these two specific circumstances and imposed a sentence materially more favorable to the defendant. See Coles, 403 F.3d at 767; United States v. Saro, 24 F.3d 283, 288 (D.C.Cir.1994).
Recognizing the hurdle posed by relying on arguments that he could have asserted at sentencing, Simpson added a new twist to his “fast-track” disparity contention at oral argument. Noting that prior to Booker he could not have anticipated how post-Booker courts would treat unlawful re-entrants, Simpson complained that he was therefore disabled from pointing out disparities in the way that border and non-border courts would sentence such offenders after Booker. In short, Simpson insisted he could not effectively make a § 3553(a)(6) argument based on fast-track disparities until a post-Booker track record of such disparities developed.
This argument proves too much. Thanks to its prescience regarding the fate of the Guidelines, Simpson’s sentencing court was in approximately the same position as that of the first district courts to render sentences after Booker. Yet it cannot be argued that those early post-Booker sentences must also be vacated because their recipients did' not have the opportunity to compare their sentences with sentences imposed even later. Indeed, on Simpson’s theory, no sentencing could ever be the first. Each would have to await others so that there could be a basis for comparison — which, of course, means that no sentencing could ever occur.
Simpson’s argument does not fail' merely because of this reductio ad absurdum. It also fails because it is inconsistent with Booker itself. There, the Supreme Court remanded for the resentencing of defendants Booker and Fanfan, without any suggestion that the district courts should wait until a track record was established by other courts. 125 S.Ct. at 769. Thus, 18 U.S.C. § 3553(a)(6), which requires sentencing courts to consider “the need to [1190]*1190avoid unwarranted sentence disparities among defendants with similar records who have been found guilty of similar conduct,” id. (emphasis added), must be read to refer to disparities with past and present sentences — not with hypothetical future ones.
In sum, we find no cognizable error in the alternative rationale that the district court provided for its sentencing calculation, and hence no cognizable error in the 46-month sentence that the court imposed on Simpson.
IV
This opinion has proceeded on the basis that, if there is no error in a district court’s alternative sentencing rationale, there is no error in the sentence the court imposed.13 Appellate panels in the Sixth and Eighth Circuits have suggested a similar analysis.14 Other circuits have taken a different approach, assuming that Booker error in a district court’s primary sentence constitutes error in the judgment, and then asking whether the court’s pronouncement of a lawful alternative sentence renders that error harmless. Utilizing that approach, the circuits have frequently found such error harmless beyond a reasonable doubt.15
Were we to apply such an analysis here, we would reach the same result. Simpson’s objection to the district court’s [1191]*1191mandatory application of the Guidelines in calculating his sentence was sufficient to preserve that objection for harmless error review.16 But the existence of the alternative sentence, imposed in a manner consistent with the post -Booker sentencing regime, removes any mystery as to what the district court would have done had Booker been the law at the time of Simpson’s sentencing. Consequently, any error in the first sentence is harmless beyond a reasonable doubt.17
In opposition to this conclusion, Simpson draws our attention to a passage in a Second Circuit opinion, United States v. Crosby, 397 F.3d 103 (2d Cir.2005), which questions whether an alternative sentence can ever render Booker error harmless.18 The first sentence of the passage, and its accompanying footnote, reads as follows:
[EJven if a judge, prior to Booker/Fan-fan, indicated an alternative sentence that would'have been imposed if compliance with the Guidelines were not required, that alternative sentence is not necessarily the same one that the judge would have imposed in compliance with the duty to consider all of the factors listed in section 3553(a).*
Id. at 118 & n. 18. Unlike the judge hypothesized in Crosby, Simpson’s sentencing 'judge was particularly prescient. He did anticipate Booker’s remedial opinion and did consider the § 3553(a) factors with an awareness that he should do so on a non-mandátory basis. We are therefore confident that the alternative sentence in this case is in fact “the same one that the judge would have imposed in compliance with the duty to consider all of the factors listed in section 3553(a).” Id. at 118.
The second sentence of the cited passage from Crosby continues:
In addition, such an alternative sentence is not necessarily the same one that the judge would have imposed after presen[1192]*1192tation by the Government of aggravating circumstances or by the defendant of mitigating circumstances that existed at the time but were not available for consideration under the mandatory Guidelines regime.
Id. Again, contrary to the Crosby hypothetical, any mitigating circumstances that existed at the time were available for consideration under the alternative sentencing regime employed by Simpson’s sentencing judge. Accordingly, if there were any error, it was harmless beyond a reasonable doubt.
V
Although the district court pronounced sentence on Joseph Simpson prior to the Supreme Court’s substantial restructuring of the federal sentencing regime in United States v. Booker, the court accurately predicted the course the Supreme Court would ultimately take. Because the district court’s alternative sentencing methodology was materially consistent with that of Booker, the court’s judgment is
Affirmed.
Although the duty to comply with section 3553(a) existed prior to Booker/Fanfan, it is unlikely that a sentencing judge anticipating that decision would have anticipated the full import of the Remedy Opinion, and considered the section 3553(a) factors, including the guidelines, with awareness of the excision of the subsection [that made the Guidelines mandatory].