The Pennsylvania Supreme Court drew new boundaries for the state’s congressional districts on Monday, releasing a map that, if it stands, could play a significant role in Democratic Party efforts to gain control of the House of Representatives in the midterm elections.

The court ruled in January that the state’s existing congressional map was an illegal partisan gerrymander that “clearly, plainly and palpably” violated the State Constitution. Under that map, Republicans have repeatedly won 13 of the state’s 18 House seats.

Election analysts said that the court’s new map could result in Democrats picking up three or four more seats, based on 2016 voting patterns. Pennsylvania is a perennial battleground in statewide elections, with voters supporting the two parties in roughly equal numbers. Critics have pointed to the current imbalance in House seats to highlight the unfairness of the current map, which was drawn in 2011 by Republicans.

Republicans in the State Legislature said they would challenge the new maps in federal court.

“Implementation of this map would create a constitutional crisis where the Pennsylvania Supreme Court is usurping the authority of the legislative and executive branches,” the leaders of the State Senate, Joe Scarnati, and the House, Mike Turzai, said in a statement. “This map illustrates that the definition of fair is simply code for a desire to elect more Democrats.”