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.

The ruling appeared likely to resolve a year of legal uncertainty over the fate of the new map, which was redrawn at President Trump’s request outside the usual once-a-decade cycle. An appeal to the U.S. Supreme Court remains possible.

Officials with the secretary of state’s office and attorney general’s office in Missouri did not immediately respond to requests for comment.

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.”

Though the Missouri Supreme Court determined that it was legal for legislators to redraw the map, it also found that residents opposed to the boundaries had acted within the law when they submitted hundreds of thousands of signatures seeking a statewide referendum on the issue. The judges found that the redrawn map should have been suspended until a referendum could be held.

Missouri Republicans were among the first to heed Mr. Trump’s call to redistrict to improve their party’s chances of holding the House in the 2026 midterms. They passed their new map in September 2025 during a special session called by Gov. Mike Kehoe, a Republican who signed the new boundaries into law later that month.

Other states, including some led by Democrats, have also made attempts to redistrict, with varying degrees of success. Republicans nationally have positioned their party to pick up several seats in the House through remapping.

The redrawn Missouri map sliced the core of Kansas City, Mo., into several districts in an attempt to unseat Representative Emanuel Cleaver, one of two Democrats in the state’s congressional delegation. The new map did not significantly alter the partisan makeup of the other Democratic-held district, which is in the St. Louis area.

Redistricting opponents questioned the legality of the new map in several lawsuits that sought to revert to the old boundaries. Republicans repeatedly prevailed in Missouri courts.

Democrats and their allies also sought to force a statewide referendum but initially faced roadblocks.

Secretary of State Denny Hoskins, who is responsible for approving referendum questions, said last month that he believed redistricting was ineligible for a statewide vote. Mr. Hoskins, a Republican, waited until the day of the primary election, when voters were casting ballots based on the new district lines, to release that opinion.

That left the Missouri Supreme Court as redistricting opponents’ last chance to undo the new map. Five of the seven judges on the court were appointed by Republican governors, and two by Democrats.

In court filings, lawyers for redistricting opponents described Mr. Hoskins’s decision to wait until the day of the primary election to reject the referendum as a “tactical delay.” Even though the primary was held using the redrawn boundaries, they said, the general election in November should use the old ones.

Lawyers from the Missouri attorney general’s office dismissed those arguments in their own filing as “legally wrong and, frankly, crazy.”

The state’s lawyers said that redistricting, unlike other laws passed by the legislature, was ineligible for a referendum because the U.S. and Missouri Constitutions gave lawmakers the authority to create congressional maps. Finding otherwise, they warned, could lead to chaos.

“Every time redistricting occurs, the minority political party could easily gather the signatures needed to freeze a congressional map for one election cycle — a small price to pay for one or more congressional seats,” the state’s lawyers argued.