RALEIGH, N.C. — Federal judges on Monday rejected a request by North Carolina voters who sued over General Assembly district boundaries to hold special elections next March in new districts once lines are redrawn to eliminate illegal racial gerrymandering.

The unanimous order by the three-judge panel means the next legislative elections won’t occur until November 2018. But the judges did tell Republican lawmakers that they’ll have to approve new House and Senate boundaries by this September — at least two months earlier than GOP leaders sought.

The three judges told lawmakers to draw the new maps by Sept. 1 but wrote that they would extend the deadline to Sept. 15 if lawmakers make enough progress on new boundaries in the next few weeks.

The panel ruled in August 2016 that 28 state House and Senate districts were illegally drawn based on racial considerations. After Republicans took the case to the U.S. Supreme Court, the justices upheld the lower court decision to throw out those boundaries. Democrats hope the new boundaries could help them erode the GOP’s veto-proof majorities in both legislative chambers.

READ MORE: Supreme Court strikes down 2 redrawn districts in N.C. over racial bias

Although the three judges said they would explain their decision against a special election in a forthcoming opinion, lawyers for GOP legislative leaders have said having one would be too complicated and would overlap with the November 2018 election schedule.

In oral arguments last week in Greensboro federal court, two of the judges expressed concerns that North Carolina legislative leaders had taken few steps to draw new election maps.

The judges reaffirmed those worries in Monday’s order, writing that it appears “the General Assembly does not appreciate the need to move promptly to cure the unconstitutional racial gerrymanders” in plans first approved in 2011.

Setting the Sept. 1 deadline, the judges wrote, gives lawmakers time to hold public hearings while moving the process along.

“Constitutionally adequate districts should be enacted as quickly as possible to protect the rights of North Carolina citizens and to minimize any chilling effect on political participation attributable” to the lack of a lawful plan, the order said.