Virginia voters head to the polls Tuesday to choose party nominees for the U.S. Senate and House, opening the commonwealth’s third statewide election in nine months and setting the stage for November’s general election.

The primary will be conducted under Virginia’s existing congressional boundaries after the Virginia Supreme Court voided a voter-approved map in April, less than three weeks after voters approved it. The rejected map was more favorable to Democrats, according to the Associated Press, leaving the previous district lines in place for this election.

The court’s ruling revived the political stakes surrounding Virginia’s congressional map. The Virginia Supreme Court’s decision to void the Democrats’ congressional map ensures that voters will choose nominees in districts that could look very different if redistricting fights return after the election.

Several Virginia districts are competitive enough to affect which party controls the narrowly divided U.S. House after November, the Associated Press reported. That makes Tuesday’s contests more than a routine nomination round: they are the first test of the parties’ strength in races that could determine the balance of power in Washington.

The Virginia map fight also unfolded amid a broader Republican effort to redraw congressional boundaries ahead of schedule. President Donald Trump and lawmakers in Republican-controlled states, including Texas and Missouri, pushed to revise their maps early and improve their party’s chances of holding the House. The Associated Press described that effort as largely successful, while Virginia’s replacement map failed in court.