Early this month, a three-judge panel of the U.S. District Court for the Middle District of North Carolina ruled that maps for two districts were unconstitutional, and ordered the state to redraw their lines within two weeks. The panel said that race played an impermissible role in the drawing of the districts.

The state redrew the maps but asked the Supreme Court to grant a stay that would allow the old maps to remain in effect pending further appeal.

Late Friday, the Supreme Court declined to do so. As customary, it did not release the vote tally for the decision.

One election law expert believes that before Justice Antonin Scalia's death the Court would have granted the stay.

"Before the death of Justice Scalia, I had thought the Court would grant the stay, not because there would be a majority of justices who would necessarily agree on the merits, but because there were likely at least five who would see the problem of changing the rules so close to the election," said Rick Hasen, professor of law and political science at the University of California Irvine School of Law.

The ruling may cause irritation on the ground.

"It's a real mess with risk of confusion," said Michael Li of the Brennan Center for Justice. "With the new maps, congressional primaries will be delayed until June 7, but the presidential primary and rest of the North Carolina primary elections will still be in March," he said.