The Supreme Court upheld a pro-Republican South Carolina congressional map Thursday, rejecting the argument raised by civil rights groups that lawmakers impermissibly used race as a proxy to bolster the GOP’s chances.

But the high court also said that the civil rights groups that challenged the maps could continue to pursue one part of their claim, a move that will likely delay the battle over the districts for months.

With state election deadlines approaching, a federal court in March had already ruled that South Carolina could use the contested map in this year’s election.

The decision was 6-3 along conservative-liberal lines.