JEFFERSON CITY, Mo. — The Missouri Supreme Court has unanimously blocked new congressional districts backed by President Donald Trump from being used in the November election and ordered a statewide vote on whether to uphold or reject the new map.

The decision Thursday marks a rare setback for Republicans in a national redistricting battle. Republicans had hoped Missouri's new congressional boundaries could help them win an additional seat and hold onto their slim House majority in the midterms.

Missouri Attorney General Catherine Hanaway, a Republican, said she would immediately appeal to the U.S. Supreme Court, asserting that the decision “has thrust our state into a full‑fledged constitutional crisis.”

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 ruled that the new districts were effectively placed on hold in December, when opponents submitted over 300,000 petition signatures seeking to put the map to a vote of the people. 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, but the Supreme Court overturned Hoskins' decision.

“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 “remains in full force and effect for the November 2026 general election.”

Hanaway, whose office represented Hoskins, called the ruling an unprecedented violation of federal law.

“Never before in American history has a court overturned a congressional map after a primary and before a general election," Hanaway said in a statement.

The Missouri Constitution does not specifically say a referendum petition can be used for a congressional redistricting law passed by the Legislature. But the Supreme Court ruled that a constitutional provision allowing a referendum on “any act” of the Legislature encompasses congressional redistricting. It rejected assertions from Hanaway's office that federal law prohibits referendum petitions on congressional redistricting.

The ruling, which capped a year of political maneuvering and legal wrangling, was one of two to go against Republican officials Thursday. The Supreme Court also ruled that Hoskins had wrongly rejected a petition for a ballot proposal making it difficult for politicians to change measures enacted by voters through citizen initiatives. The court also ordered that measure to be placed on the November ballot.

Missouri redistricting targeted longtime Kansas City lawmaker

Missouri currently has six Republicans and two Democrats in the U.S. House.

After 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 Democrat Emanuel Cleaver.

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 eastward to include rural Republican areas. About 59% of the 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.

Redistricting battle spread to over a quarter of states

Congressional districts typically are redrawn at the start of each decade, based on new census data. But 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.”

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