WASHINGTON (AP) — The Supreme Court on Tuesday temporarily blocked the counting of some mail-in ballots in Pennsylvania, an order that could affect the tight Republican Senate primary between former hedge fund CEO David McCormick and celebrity heart surgeon Dr. Mehmet Oz.

An order from Justice Samuel Alito paused a lower-court ruling in a lawsuit over a disputed 2021 local court election that would have allowed the counting of mail-in ballots that lacked a handwritten date.

The 3rd U.S. Circuit Court of Appeals in Philadelphia had ruled that the state election law’s requirement of a date next to the voter’s signature on the outside of return envelopes was “immaterial.”

Based on that ruling, the state had advised counties to count those ballots in the race between McCormick and Oz.

As McCormick scrounges for ballots to make up the gap with Oz, Alito’s order also could freeze a separate federal lawsuit in Pennsylvania in which McCormick is fighting to force counties to count the ballots.

The high court’s action, called an administrative stay, freezes the matter until the court can give it further consideration.

The state law requires voters to write a date on the envelope in which they mail in their ballots. However, the envelope is postmarked by the post office and timestamped by counties when they receive it.