Prediction market traders now give Democrats a slight edge to take control of the U.S. Senate, with speculators on Kalshi pricing a 54% chance of a Democratic win and Polymarket traders putting the odds at 59%. Republicans are defending majorities in both the U.S. House of Representatives and Senate this November, and the upper chamber has long been viewed as the harder flip for Democrats, who would need to capture several states President Donald Trump won by 10% or more in 2024, including Alaska, Texas and Ohio. Republicans already control 20 of the 33 Senate seats up for grabs this year. Before the U.S.-Iran war began on Feb. 28, Republicans had about 60% odds to hold the Senate on both Kalshi and Polymarket, but those odds declined as rising gas prices drove down Trump's approval rating, and Democratic odds briefly topped Republican odds in April before the GOP recovered in May and through the summer as the war deescalated. GOP fortunes have darkened again in recent weeks, with U.S. oil prices now above $100 per barrel, gasoline above $4 a gallon nationally and diesel prices at an all-time high, and prediction market traders now think gas prices will hit new highs this year. A New York Times/Siena University poll released Wednesday showed likely voters nationwide favoring Democratic candidates over Republicans in their congressional districts by close to 9 percentage points.
