FILE PHOTO: A view of the U.S. Supreme Court in Washington, U.S. June 29, 2024. REUTERS/Kevin Mohatt/File Photo

By Andrew Chung

(Reuters) -The U.S. Supreme Court agreed on Monday to hear Mississippi's defense of a state law challenged by Republicans that allows a five-day grace period for mail-in ballots received after Election Day to be counted, a case that could lead to stricter voting rules around the country.

The justices took up Mississippi's appeal of a lower court's ruling that deemed illegal the state law that permits mail-in ballots sent by certain voters to be counted if they were postmarked on or before Election Day but received up to five business days after a federal election.

The court is expected to hear arguments and issue a ruling by the end of June.

The Republican National Committee, the Mississippi Republican Party and other plaintiffs filed a lawsuit seeking to invalidate Mississippi's law in 2024.

Republican President Donald Trump in August vowed to end the use of mail-in ballots nationwide before the 2026 U.S. midterm elections, a move that likely would disproportionately benefit his party given that Democratic voters traditionally have been more likely to use mail-in ballots than Republican voters.

About 30 states and the District of Columbia accept at least some ballots that are postmarked on or before Election Day but received afterward.

During the first year of the COVID pandemic, the Republican-controlled Mississippi legislature in 2020 passed the challenged law on a bipartisan basis. In Mississippi, absentee voting by mail is limited to a few categories of voters, including elderly people, the disabled and those living away from home.

The New Orleans-based 5th U.S. Circuit Court of Appeals ruled in favor of the challengers to the law in 2024. It declared that the Mississippi law was preempted by federal laws setting Election Day for federal elections as the "day by which ballots must be both cast by voters and received by state officials."

Federal law "does not permit the state of Mississippi to extend the period for voting by one day, five days or 100 days," the 5th Circuit's ruling stated.

The 5th Circuit did not immediately block Mississippi's procedures, but instead sent the case back to a trial judge for further review. The litigation is currently on hold pending the Supreme Court's consideration.

Though the 5th Circuit's action applied only in the three states where the regional federal appeals court has jurisdiction - Mississippi, Louisiana and Texas - it called into question the voting practices in the other states with similar mail-in ballot policies.

Republicans have taken a skeptical view toward mail-in ballots. Trump has sought to cast doubt on the security of these ballots, although evidence of voter fraud is rare. Trump has made false claims that he, not Democrat Joe Biden, won the 2020 presidential election.

Mississippi told the Supreme Court in its appeal that the 5th Circuit's decision invites litigation nationwide against laws in most states, "risking chaos in the next federal elections, particularly given the tendency of election law claims to spur last-minute lawsuits."

(Reporting by Andrew Chung in New York; Editing by Will Dunham)