Missouri voters face Proposition A on November 3, 2026, a veto referendum on House Bill 1, the 2025 congressional redistricting plan enacted by Republican lawmakers during a special session and signed by Governor Mike Kehoe. The measure, backed by President Trump, would replace the 2022 map with lines projected to flip one Democratic-held district. Opponents gathered over 300,000 signatures to suspend the plan, prompting legal challenges that reached the Missouri Supreme Court. That court unanimously ruled the referendum constitutional in September 2026, keeping the 2022 boundaries in effect for the current election cycle while U.S. Supreme Court review did not alter the outcome. Missouri’s history of voters rejecting legislative redistricting efforts via referendum, combined with the mid-decade partisan character of the redraw, supports the current trader consensus favoring rejection.