Missouri voters face Proposition A on November 3, 2026, a veto referendum on House Bill 1, the congressional map enacted in a 2025 special session under Republican control. A yes vote would uphold the new boundaries, which shift the delegation toward a 7-1 Republican advantage by splitting Kansas City across districts. A no vote would reject the map and preserve the 2022 lines. Missouri Supreme Court rulings cleared the measure for the ballot after signature verification and constitutional challenges, while federal courts confirmed use of the prior map for the 2026 election. An August SLU/YouGov poll showed 35% yes, 32% no, and 33% undecided on the official ballot language, reflecting divided sentiment amid the mid-decade redistricting effort and campaign spending by groups on both sides. Trader consensus on rejection aligns with the high undecided share and historical patterns for such referendums.