Missouri voters will decide Proposition A, a veto referendum on House Bill 1, the 2025 congressional redistricting plan, on November 3. The measure, enacted in a special session and signed by Governor Mike Kehoe, redraws districts to favor Republicans, including splitting Kansas City across three GOP-leaning seats. Following a citizen petition drive that gathered over 300,000 signatures, the Missouri Supreme Court unanimously ruled the referendum valid after the secretary of state initially blocked it, suspending HB 1 until voter approval and requiring use of the 2022 map for the 2026 election. The U.S. Supreme Court declined further review. Traders assign a 73% probability to rejection, reflecting the plan’s mid-decade partisan origins, Missouri’s prior voter rejections of legislative redistricting changes, and organized opposition campaigns.