The Supreme Court announced on Monday that it will review the legality of states accepting mail-in ballots that arrive after polls close, provided they are postmarked by Election Day. This decision comes as preparations for next year’s midterm elections intensify.

The Republican National Committee (RNC) has challenged this practice, successfully persuading a lower court that Mississippi’s law is overridden by federal regulations.

In a concise order, the Supreme Court agreed to examine Mississippi’s appeal to reverse the previous ruling. Oral arguments are anticipated next year, with a verdict expected by summer, potentially influencing voting procedures for the 2026 midterm elections.

According to federal law, Election Day is designated as the first Tuesday of November. Republicans argue that states accepting ballots post-Election Day violate this stipulation.

Currently, 16 states permit the counting of ballots that arrive after Election Day, as reported by the National Conference of State Legislatures.

The Supreme Court battle pits the RNC against GOP officials in Mississippi defending its law. The state urged the justices to get involved now, saying a resolution was needed before next year’s contests. 

“The stakes are high: ballots cast by—but received after—election day can swing close races and change the course of the country,” the state attorney general’s office wrote. 

The RNC acknowledged the issue is important, but it argued the lower court got it right and didn’t merit the justices’ review. 

“It should await a case where the lower court answers the question presented incorrectly, should one ever arise,” the RNC wrote in court filings. 

Already this term, the court agreed to decide who has the legal right to bring such lawsuits. Rep. Michael Bost (R-Ill) and two of Trump’s electors are appealing a ruling that found they can’t challenge Illinois’ law. Oral arguments took place last month. 

But in the new case, Mississippi does not dispute that the RNC can bring its lawsuit, and lower courts agreed the party had standing to proceed, providing a cleaner path for the justices to reach the underlying legal merits of the practice.