The Missouri Supreme Court unanimously blocked a Trump-backed U.S. House map from use in the November election and held that a referendum challenging the plan is legal, sufficient, and timely. The court left the state’s 2022 congressional map in place until voters approve a change.

The ruling halts House Bill 1’s new lines after they were already used in August primaries. It also sets up an emergency fight at the U.S. Supreme Court days before a ballot deadline. Attorney General Catherine Hanaway filed that appeal on Friday. Justice Brett Kavanaugh set responses for Monday, Sept. 7, ahead of a Tuesday, Sept. 8, ballot deadline. The state court had already denied a stay.

The map was designed to remake Kansas City Democratic Rep. Emanuel Cleaver’s 5th District. An Associated Press estimate put the share of new voters in that redrawn seat at about 59 percent under the HB1 lines.

How The Referendum Forced The Issue

Opponents collected more than 300,000 petition signatures by December 2025 to put the map to a statewide vote. Secretary of State Denny Hoskins rejected the referendum on primary day. The Supreme Court reversed that rejection and found the petition met the legal tests for the ballot.

That sequence matters as much as the map geometry. Missouri’s referendum process, not a federal Voting Rights Act trial, is what stopped HB1 for November. The court did not redraw the districts itself. It said voters get a say before the new lines govern a general election.

Republicans who backed the mid-decade rewrite argued the legislature had authority to replace the 2022 map. Referendum sponsors argued the signatures were valid and that tossing them on primary day short-circuited direct democracy. The unanimous opinion sided with the sponsors on sufficiency and timing.

August Primaries Under Lines That May Not Count In November

Candidates already ran in August under the HB1 map. November would now revert to the 2022 boundaries unless a higher court intervenes or voters later approve the new plan. That mismatch creates administrative and political strain: primary electorates and general-election electorates would not be the same.

Cleaver, the clearest target of the remap, welcomed the state decision as a check on a mid-decade power play. State Sen. Rick Brattin won the Republican primary in the reshaped 5th District under those HB1 lines. Republican supporters of HB1 had cast the new map as a legitimate use of legislative power after the last election cycle. Hanaway’s office moved immediately to federal court, arguing the state ruling should not control the November ballots.

President Donald Trump criticized the Missouri decision on Truth Social, framing it as resistance to a map his allies wanted. The state court’s opinion did not turn on Trump’s endorsement. It turned on referendum law.

The Emergency Appeal To Washington

Hanaway’s emergency application asks the U.S. Supreme Court to step in before Missouri’s Sept. 8 ballot deadline. Kavanaugh’s scheduling order gives opponents a Monday response window, compressing days of briefing into a holiday weekend stretch.

Federal review would test whether a state supreme court’s reading of its own referendum rules can be displaced in time to revive a map already used in primaries. The Missouri court denied the state’s request for a stay, so HB1 remains blocked unless the justices act.

Election officials need a final answer to print and mail the correct congressional ballots. A decision after Tuesday’s deadline would land after some administrative points of no return.

What Is Settled And What Is Not

Settled in Missouri for the moment: the Supreme Court blocked HB1 for November, found the referendum valid, kept the 2022 map in force pending voter approval, and refused a state stay. Soft or pending: whether the U.S. Supreme Court will resurrect the Trump-backed lines before ballots lock, how Cleaver’s district looks if 2022 boundaries return, and how voters will treat a later referendum if the federal appeal fails.

The fight is no longer only about one Kansas City seat. It is about whether a mid-decade congressional map enacted with presidential backing can survive a state referendum process that the state’s highest court has now unanimously blessed. Monday’s filings and any order before Tuesday’s deadline will decide if November is run on the old map or the new one.