LAS VEGAS (AP) — The Republican National Committee on Friday filed a federal lawsuit seeking to prevent Nevada from counting mail ballots received after Election Day, as the state’s law currently permits.

The law, passed by Democrats in 2021, permits the tallying of mail ballots received up to four days after Election Day, provided the envelopes are postmarked before the end of the day. The lawsuit says the provision also assumes that envelopes received three days after Election Day that don’t have a postmark indicating otherwise were posted in time.

Republicans contend this violates the U.S. Constitution’s requirement that there be a single day for Election Day.

“Nevada’s ballot receipt deadline clearly violates federal law and undermines election integrity in the state,” RNC Chairman Michael Whatley said in a statement. “Ballots received days after Election Day should not be counted.”