Missouri voters will decide Proposition A on November 3, 2026, a veto referendum on House Bill 1, the 2025 congressional map enacted in a special session that redraws districts to favor Republicans with seven of eight seats. The measure reached the ballot after opponents gathered more than 305,000 signatures and the state Supreme Court unanimously upheld the referendum process in early September, blocking HB 1 from taking effect. The 2022 map remains in use for the current election cycle. Trader consensus favoring rejection at 75% reflects the map’s partisan mid-decade origins, Missouri’s historical pattern of voters repealing legislative redistricting plans through referendum, and organized opposition highlighting district changes in areas such as Kansas City. No major new developments have altered this positioning in recent weeks.