The Supreme Court of Virginia invalidated a voter-approved redistricting referendum on Friday, ruling that lawmakers failed to follow the constitutional process required to place the measure on the ballot and halting Democrat-led efforts to implement a new congressional map.

The 4-3 majority opinion, written by Justice D. Arthur Kelsey, held that lawmakers acted too late when they approved the amendment proposal after more than a million early ballots had already been cast in last year’s Virginia elections. The state constitution requires the legislature to vote on any proposed constitutional amendments in two stages with an election in between to give voters the opportunity to weigh the amendment when they vote for their representatives, and the state Supreme Court found that Virginia Democrats did not follow that process.