The Supreme Court’s March 2026 oral arguments in Watson v. Republican National Committee signaled a likely ruling that federal Election Day statutes require mail ballots to be both cast and received by that date, overturning Mississippi’s grace period for postmarked ballots arriving up to five days later. Conservative justices expressed skepticism toward state laws permitting late receipt, aligning with the RNC’s challenge and similar provisions in roughly 14 states plus D.C. A decision expected by late June or early July would directly affect ballot counting in the 2026 midterms. Traders assign the 76.5% implied probability to “yes” based on the Court’s composition, the Fifth Circuit precedent, and consistent signals during argument that federal law preempts extended receipt deadlines.