Momentum has shifted toward Democrats in Kalshi’s Senate control market. On Monday, traders assigned the party a 74% chance of winning control of the chamber, marking its strongest position on the platform since the market launched in 2024.
The change followed a New York Times and Siena University poll showing Democrats ahead in several battleground states. The Kalshi contract asks who will control the Senate and is set to be verified by the Library of Congress after Tuesday’s vote.
Republicans had dominated the market for Senate control during much of the 2026 cycle. The gap between the parties narrowed after the United States and Israel launched strikes on Iran on February 28, although Republican odds later rose to 60% in July before reversing in mid-September.
Individual Senate race markets have also moved toward Democratic candidates over the past 24 hours. On Kalshi, the probability of a Democratic victory in Texas rose to 74%, from 68.4%. On Polymarket, the Democratic odds in Iowa increased to 50%, up from 42%.
In Kansas, where no Democratic U.S. senator has been elected since 1932, the odds of Democratic candidate Adam Hamilton defeating Republican Roger Marshall climbed to 63%, compared with 52% previously.
Prediction markets and betting platforms use methods different from those employed by traditional political polls and should not be treated as substitutes for polling.
CNBC disclosed that it has a commercial relationship with Kalshi involving customer acquisition and a minority investment.
Sources: CNBC Markets.