The Supreme Court on Friday night left in place a ruling by Pennsylvania’s highest court that requires election boards in the state to count provisional ballots submitted by voters whose mail-in ballots had been deemed invalid.

The brief unsigned order came just four days before election day. Recent polls show former President Donald Trump and Vice President Kamala Harris tied in Pennsylvania, which both candidates regard as a key part of their hopes of winning the White House. The Republican National Committee and the Republican Party of Pennsylvania, which had sought to block the ruling by the Pennsylvania Supreme Court, told the justices that their decision could affect “tens of thousands of votes,” but at least one voting rights expert believes that the number of ballots at stake could be relatively low.