The Supreme Court’s March 23, 2026, oral arguments in Watson v. Republican National Committee showed a conservative majority questioning state laws that count mail ballots postmarked by Election Day but received days later. Federal statutes establishing a single Election Day appear central to the challenge against Mississippi’s five-day grace period, with similar rules in fourteen states and the District of Columbia. Justices focused on whether these provisions conflict with the uniform federal deadline, raising the prospect of a nationwide bar on late-arriving ballots ahead of the 2026 midterms. A decision is expected by late June or early July. This judicial posture has shaped trader assessments of the likelihood that the Court will require all ballots to be received on or before Election Day.