The Virginia Supreme Court on Friday struck down a voter-approved Democratic congressional redistricting plan, delivering another major setback to the party in a nationwide battle against Republicans for an edge in this year’s midterm elections.

The court ruled that the state’s Democratic-led legislature violated procedural requirements when it placed the constitutional amendment on the ballot to authorize the mid-decade redistricting. Voters narrowly approved the amendment April 21, but the court’s ruling renders the results of that vote meaningless.

“This violation irreparably undermines the integrity of the resulting referendum vote and renders it null and void,” the court said in its opinion.

Democrats had hoped to win as many as four additional U.S. House seats under Virginia’s redrawn U.S. House map as part of an attempt to offset Republican redistricting done elsewhere at the urging of President Donald Trump. That ruling, combined with a recent U.S. Supreme Court decision severely weakening the Voting Rights Act, has supercharged the Republicans’ congressional gerrymandering advantage heading into this year’s midterm elections.

Legislative voting districts typically are redrawn once a decade after each census to account for population changes. But Trump started an unusual flurry of mid-decade redistricting last year when he encouraged Republican officials in Texas to redraw districts in a bid to win several additional U.S. House seats and hold on to their party’s narrow majority in the midterm elections.