The Missouri Supreme Court has unanimously blocked the state from moving forward with a new House map that favors Republicans in this year’s midterm elections, ordering a statewide vote on whether to uphold or reject the new map.

The decision Thursday marks a rare setback for Republicans in the national redistricting battle, as they fight to hold onto their slim House majority. It’s also a massive win for longtime Democratic Rep. Emanuel Cleaver, whose Kansas City-area district was set to be redrawn to tilt it toward the GOP.

The ruling still could be appealed to the U.S. Supreme Court.

Missouri’s new districts were used in the August primaries. But the state Supreme Court said they cannot be used in the November general election — or ever again, unless voters first uphold the new districts passed by the Republican-led legislature.

The court placed the new districts on hold because citizens submitted petition signatures seeking a referendum.

“The referendum petition was legal, sufficient, and timely, and the secretary incorrectly concluded otherwise,” the court said in its ruling. The legislation containing the new districts “did not go into effect and will not go into effect unless and until approved by the voters.” 

As a result, the congressional map adopted after the 2020 census — with six GOP-leaning and two Democratic-leaning districts —
“remains in full force and effect for the November 2026 general election.”

The Missouri Constitution does not specifically say a referendum petition can be used for a congressional redistricting law passed by the Legislature. But the state Supreme Court ruled that a constitutional provision allowing a referendum on “any act” of the legislature encompasses congressional redistricting.

The ruling capped a year of political maneuvering and legal wrangling over the new districts.

After President Trump urged Republicans to redraw congressional districts to their advantage, Missouri Gov. Mike Kehoe called lawmakers into a special session last year to dramatically reconfigure the 5th Congressional District, held by Cleaver.

Opponents submitted over 300,000 petition signatures in December seeking to put the map to a vote of the people. But Republican Secretary of State Denny Hoskins waited until primary election day in August to reject the petition. He asserted that the referendum process cannot be used for congressional redistricting. A lower court agreed, resulting in an appeal to the state’s highest court, which overturned Hoskins’ decision.

Attorneys representing Hoskins and Republican Party committees had argued it was too close to the general election to revert to the prior districts without causing confusion and chaos.

Cleaver, who was unopposed in the August primary, has carried the Kansas City-based district with at least 60% of the vote in each of the past two elections.

Republican state Sen. Rick Brattin won an August primary in the reshaped 5th Congressional District, which had been stretched more than 100 miles eastward to include rural Republican areas. About 59% of the 5th District’s voters were new under the revised map, according to an Associated Press estimate. 

Cleaver had not posted campaign signs in many of the new rural areas, explaining that he was waiting for the Missouri Supreme Court’s decision. But he had vowed to continue his reelection campaign regardless of the outcome.

“We’re going to run, and we’re going to run hard, no matter where we are,” Cleaver said last month at the Missouri State Fairgrounds in Sedalia, which had been added to the revised 5th District.

Brattin, a Marine veteran and founding member of the conservative Missouri Freedom Caucus in the state Legislature, had questioned whether Cleaver could represent a wider district.

“I think his whole campaign strategy was hoping that the courts would do his bidding for him. I don’t think that he represents Missouri values,” Brattin had said at the State Fair.

Congressional districts typically are redrawn at the start of each decade, based on new census data. But Mr. Trump’s quest for a midterm election advantage triggered an unusual mid-decade redistricting battle that spread to more than a dozen states — and triggered a dozen lawsuits in Missouri alone. All told, Republicans had hoped to net as many as 10 additional seats nationally.

The Missouri Supreme Court ruling was one of only a few nationally to go against Republicans’ redistricting plans.

Prior to its latest ruling, Missouri’s top court already had rejected claims that the special session was illegal, mid-decade redistricting isn’t allowed and the new districts aren’t compact enough.

The group People Not Politicians spearheaded the referendum petition.

A couple hundred people chanted “Let us vote!” while rallying Wednesday outside the state Supreme Court. Grant Christensen, of Jefferson City, said he had signed the referendum petition to put the map to a vote.

“Gerrymandering is the same as voter suppression,” Christensen said. “Cutting up districts in order to steer them to vote one way or the other is not fair.”