Kalshi traders put the Democrats' chances of controlling the Senate at 74% and the House of Representatives at 94% on the eve of the US midterm elections. The platform's figures were recorded at noon ET on November 2, a day before the vote. Polymarket US shows 76% for Democrats in the Senate and 94% in the House on its page.
Republicans currently hold 53 Senate seats and Democrats hold 47. Democrats need a net gain of four seats. With a gain of three, the chamber would split 50-50, and Vice President JD Vance would give Republicans the deciding vote. The House has 435 seats, and a majority is 218. Democrats need a net gain of only three seats there.
Polymarket US gives 75% to the scenario where Democrats win both chambers and 20% to the scenario where Democrats win the House and Republicans keep the Senate.
A handful of states will decide the Senate. On Kalshi, the race in Iowa is almost even: Democrat Josh Turek gets 52%, and Republican Ashley Hinson gets 48%. In Kansas, Democrat Adam Hamilton is rated at 63%. In Ohio, Sherrod Brown stands at 71%. In Maine, Troy Jackson is at 73% against incumbent Senator Susan Collins.
The Senate result may take a while to settle. The contract will close early if four of the eight media outlets named in the rules call the same outcome without any discrepancies. If that does not happen, the party of the Senate's acting president pro tempore on February 1, 2027 will determine the outcome.
Movement over the past month has been modest. Kalshi gave Democrats about 63% for the Senate on October 2, and by November 2 that figure had risen to 74%. In the House, the rise over the same period was about two points, from 92% to 94%.
For markets, the uncertainty now centers on the Senate. The House contract sits at 94% on both platforms, while the Senate outcome depends on several states and on how quickly media outlets call the results.
