The US Supreme Court Tuesday issued an order temporarily blocking the counting of some Pennsylvania mail-in ballots that do not have a handwritten date on their declaration forms. This US Supreme Court ruling, which did not include the Court’s reasoning, could affect the close Republican US Senate primary election in Pennsylvania between David McCormick and Dr. Mehmet Oz, currently undergoing an automatic recount. While the immediate impact of the Court’s order is unknown, it could affect each ballot’s individual validity.

The court stayed a US Court of Appeals for the Third Circuit decision pending appeal. The decision pertained to a Lehigh County Court of Common Pleas election where five voters and one candidate sued the county’s elections board for not counting undated mail-in ballots. Judge Theodore McKee ordered that the mail-in ballots be counted in his opinion.

According to the Associated Press, the state of Pennsylvania directed counties to count undated mail-in ballots pursuant to the Third Circuit’s ruling. McCormick has also cited this ruling in his motion asking the Pennsylvania Commonwealth Court to order that undated mail-in ballots be counted.

Oz’s campaign Monday filed a motion to submit an amici curie brief regarding an emergency stay application from David Ritter, a defendant in the Third Circuit case. Oz argues that McCormick’s request to count the ballots is equivalent to asking Pennsylvania courts to alter the primary election rules post-voting, “to overrule their prior precedent,”  and to count ballots that “are invalid under Pennsylvania law.”