The Missouri Supreme Court cleared the way on Thursday for the state’s voters to decide in November whether to keep new congressional district boundaries redrawn to benefit Republicans. The judges ruled unanimously that the old map would be used in the November general election, a decision that at least temporarily thwarts Republicans’ efforts to pick up a House seat in the Kansas City area.

Missouri’s primary election was held last month using the redrawn boundaries, and state election officials had vowed to forge ahead with using those borders in November unless explicitly told otherwise. The seven judges did exactly that in their ruling, which came a day after oral arguments in the case and less than a week before the deadline to finalize the November ballot.

The redrawn map “did not go into effect and will not go into effect unless and until approved by the voters,” Judge Ginger K. Gooch, who was appointed by a Republican governor, wrote in the opinion. The prior map, she added, “remains in full force and effect for the November 2026 general election.” The court did not specify how candidates would be determined for a general election using the older borders since congressional nominees were selected using the redrawn ones.

Richard von Glahn, the leader of the group that organized the referendum, said in a statement on Thursday that “this is what democracy looks like.” “In a year when map-drawing has become a national weapon, courts across the country are watching what happens here,” said Mr. von Glahn, the executive director of People Not Politicians Missouri. “A Missouri win for the referendum is a signal that the people still hold the power.”