Republicans brought this case to the 5th Circuit, which is the most conservative in the country, but it could have wide-ranging implications nationally.

A conservative appeals court raised concerns that Republicans’ arguments for forbidding the counting of mail ballots that arrive after Election Day require throwing out votes cast before Election Day.

An election-law case about to be heard by a conservative federal appeals court panel in New Orleans could — if it reaches the Supreme Court — invalidate millions of absentee ballots in numerous states,