The Supreme Court signaled Monday it may be open to blocking a state ruling on partisan gerrymandering at the behest of Pennsylvania’s Republican leaders.

Last week Pennsylvania’s high court struck down the state’s election districts on the grounds they were drawn to give the GOP a 13-5 majority of its seats in the House of Representatives.

Unlike other recent rulings, the state justices said they based their ruling solely on the state’s constitution. Usually, the U.S. Supreme Court has no grounds for reviewing a state court ruling that is based on state law.

The Pennsylvania decision, if it stands, could be significant in November when Democrats hope for big gains in Congress. The state justices ordered a new election map to be drawn in the month ahead, and legal experts predicted it could shift two or three seats toward the Democrats.

Late last week, the leaders of Pennsylvania’s Legislature filed an emergency appeal with Justice Samuel A. Alito Jr. seeking an order by Jan. 31 that would block the Pennsylvania ruling. They said it conflicted with a provision in the U.S. Constitution that says members of the House will be elected under rules “prescribed in each State by the Legislature thereof.” As precedent, their lawyers cited the Bush vs. Gore ruling in 2000 in which the justices overruled the Florida Supreme Court and ended a manual recount of thousands of paper card ballots.

Alito, who reviews emergency appeals from Pennsylvania and two other states, could have denied the appeal if he thought it had no chance of being granted. But late in day Monday, he asked for a response by Feb. 4 from the League of Women Voters.

His action suggests that he believes there is some prospect that a majority of his colleagues may grant the appeal.

On Jan. 18, the court intervened in a North Carolina case at the behest of the state’s Republican leaders and put on a hold a federal court ruling that struck down its congressional map as unfairly partisan.