Case: 20-50407 Document: 00515441096 Page: 8 Date Filed: 06/04/2020 No. 20-50407 Clinton v. Jones, 520 U.S. 681, 708 (1997). III. When evaluating the first factor, “[i]t is not enough that the chance of success on the merits be better than negligible.” Nken, 556 U.S. at 434 (quotation marks omitted). Indeed, in the mine run of appeals, “likelihood of success remains a prerequisite,” 10 and a “presentation of a substantial case . . . alone is not sufficient.” 11 In a limited subset of cases, a “movant need only present a substantial case on the merits” if (1) “a serious legal question is involved” and (2) “the balance of the equities weighs heavily in favor of granting the stay.” 12 A. The state officials claim three jurisdictional bars: (1) The plaintiffs’ claims present a nonjusticiable political question; (2) the plaintiffs lack standing; and (3) the claims are barred by sovereign immunity. 13 We address United States v. Transocean Deepwater Drilling, Inc., 537 F. App’x 358, 361 (5th Cir. 2013) (per curiam) (emphasis added and brackets omitted) (quoting Ruiz v. Estelle, 666 F.2d 854, 857 (5th Cir. 1982)). 10 Wildmon v. Berwick Universal Pictures, 983 F.2d 21, 23 (5th Cir. 1992) (per curiam); see also Weingarten Realty Inv’rs v. Miller, 661 F.3d 904, 910 (5th Cir. 2011) (“[Movant] argues that a finding that he is likely to succeed on the merits is not necessary if the balance of the equities is strongly in his favor . . . . Our caselaw, however, is to the contrary.”). 11 Arnold v. Garlock, Inc., 278 F.3d 426, 439 (5th Cir. 2001) (emphasis added); see also Weingarten, 661 F.3d at 910 (“[T]his court determined that the four-factor test [for a stay] must be fully applied except where there is a serious legal question involved and the balance of equities heavily favors a stay.”). 12 In addition to their jurisdictional points, the state officials maintain that the district court should have abstained under Railroad Commission of Texas v. Pullman Co., 312 U.S. 496 (1941). Because the Texas Supreme Court has since ruled in the state officials’ favor as to the meaning of “disability” under the Texas Election Code, that issue is moot. Nevertheless, the district court’s decision to forge ahead despite an intimately intertwined—and, at that time, unresolved—state-law issue was not well considered. 13 “For Pullman abstention to be appropriate it must involve (1) a federal constitutional challenge to state action and (2) an unclear issue of state law that, if resolved, would make it unnecessary for us to rule on the federal constitutional question.” Moore v. Hosemann, 8