The U.S. Capitol building is seen on March 27, 2026 in Washington, DC.

Samuel Corum | Getty Images

The 2026 U.S. midterm election will be held a week from Tuesday, with the Republican Party looking to defend majorities in both the House and Senate , though Democrats are seen as two-to-one favorites to flip both chambers blue on prediction markets .

Speculators on platform Kalshi place a 63% chance that Democrats win control of both the House and Senate. Those odds have stayed relatively stable since the beginning of October. Meanwhile, there's just under a 10% chance that Republicans sweep both chambers, and a 29% chance Democrats win the House while the GOP maintains its majority in the Senate.

Contracts on the market are resolved using official data from the U.S.…