The 5-4 decision rejected a Republican-led attack on laws in more than half the states and the District of Columbia that permit mailed ballots to arrive and be counted some number of days after the election, provided they are postmarked by Election Day. The outcome spares officials the headache of changing their ballot rules just a few months before the 2026 midterm congressional elections.

In just over half those states, the more forgiving deadlines apply only to ballots cast by military and overseas voters.

Justice Amy Coney Barrett wrote the court’s majority opinion, joined by Chief Justice John Roberts and the three liberal justices.

Federal laws setting a single Election Day “leave open when those votes must be received,” Barrett wrote.

Congress could change the law, she said. “If varied deadlines for ballot receipt similarly call for a national solution, the American people must choose it through their elected representatives,” Barrett wrote.

The legal challenge was part of Trump’s broader attack on most mail balloting, which he has said breeds fraud despite strong evidence to the contrary and years of experience in numerous states. Trump has repeatedly claimed that his loss to Joe Biden in 2020 resulted from fraud even though more than 60 court decisions and his own attorney general said that argument had no merit.

Trump called the court ruling a “tremendous loss” and renewed his call for Congress to pass the SAVE America Act, which has made it through the House of Representatives but not the Senate.

“There is only one reason to oppose — CHEATING!” Trump wrote on Truth Social.

The court heard arguments in March in a case from Mississippi pitting the state against Trump’s Republican administration and the Republican and Libertarian parties. At issue was whether federal law sets a single Election Day that requires ballots to be both cast by voters and received by state officials.

The federal appeals court in New Orleans struck down a Mississippi law allowing ballots to be counted if they arrive within five business days of the election and are postmarked by Election Day.

The outcome is a “sigh of relief” for a lot of election administrators, said Stephen Richer, a Republican and the former top election administrator in Arizona’s Maricopa County, which includes Phoenix.

A ruling in favor of the Republican National Committee “would have created a whole host of administrative challenges for the affected states,” said Richer, who is now a legal fellow at the Cato Institute.

RNC officials did not immediately respond Monday to email and telephone requests for comment.