The U.S. Capitol in Washington, July 22, 2026.
Aaron Schwartz | Bloomberg | Getty Images
The race for the U.S. Senate remains highly competitive, yet prediction market traders indicate that Democrats have one of their strongest opportunities to seize control of the upper chamber.
Current forecasts on Kalshi assign Democrats a 54% probability of winning the Senate, almost matching the peak reached in mid-April. On Polymarket, the probabilities are even higher, showing a 59% chance that Democrats will take control.
Republicans currently hold majorities in both the U.S. House of Representatives and the Senate heading into November, but the upper chamber has historically been more challenging for Democrats to flip. With Republicans defending 20 of the 33 seats up for grabs, Democrats must win several states where President Donald Trump secured victory by 10% or more in 2024—such as Alaska, Texas, and Ohio—to regain the chamber.
Democrats’ chances of winning the Senate have improved markedly on prediction markets this year. Prior to the onset of the U.S.-Iran conflict on February 28, Republicans held approximately a 60% chance of retaining the Senate on both Kalshi and Polymarket. These odds declined as escalating gas prices eroded Trump’s approval rating.
While Democrats briefly surpassed Republican odds in April, the GOP’s prospects recovered in May and through the summer as the U.S. and Iran de-escalated tensions, alleviating pressure on gas prices.
Recent developments have worsened the GOP’s outlook. U.S. oil prices have surpassed $100 per barrel, national gasoline prices exceed $4 per gallon, and diesel costs have reached an all-time high. Prediction market traders now anticipate that gas prices will reach new peaks this year.
A wave of recent high-quality polls indicates a favorable political environment for Democrats heading into November. A New York Times/Siena University poll released Wednesday revealed that likely voters nationwide prefer Democratic candidates over Republicans in their respective congressional districts by nearly 9 percentage points.
Disclosure: CNBC and Kalshi maintain a commercial relationship that encompasses customer acquisition and a minority investment.
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