David McCormick’s campaign filed a lawsuit Monday afternoon arguing that election officials must count mail-in and absentee ballots that lack a date on their envelope, citing a federal court order released on Friday.

McCormick and his primary opponent, Mehmet Oz, have been squabbling over whether undated ballots should be counted. The fight began late last week, after a three-judge panel on the federal 3rd Circuit Court of Appeals issued a judgment that undated ballots in a 2021 county judgeship election should be counted.

McCormick’s lawsuit, filed in state court, sues the state’s chief election official and county election boards in order to compel them to count the undated ballots that were returned on time.

As of 6 p.m. Monday, Oz was leading McCormick by fewer than 1,000 votes — well within the margin for an automatic recount in the state. In the days after the May 17 primary, both Oz and McCormick unleashed an army of lawyers in Pennsylvania and tapped alumni of former President Donald Trump’s 2020 campaign to help them with behind-the-scenes combat over every vote.