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Prediction market traders are now giving Democrats a slight edge to win control of the U.S. Senate, even as the race remains close.
According to CNBC, Kalshi prices Democrats at a 55% chance to win the chamber, while Polymarket puts those odds at 59%. The shift matters for anyone tracking how election markets are pricing control of Congress, including a Senate map that features a special election seat in Florida.
Kalshi and Polymarket now show a narrow Democratic advantage
The current market view marks a reversal from earlier this year. Before the Iran war began on Feb. 28, Republicans were given about a 60% chance to hold the Senate on both Kalshi and Polymarket, according to the report.
Democratic odds improved during 2026 and at one point moved ahead of Republican chances in April. CNBC reported that GOP odds later recovered in May and through the summer as the U.S. and Iran de-escalated the war, leaving the market with a tight but slightly Democratic-leaning outlook in mid-September.
The report also noted a favorable recent polling environment for Democrats. A New York Times/Siena University poll released Wednesday found likely voters nationwide preferred Democratic candidates over Republicans in their congressional districts by nearly 9 percentage points.
The Senate map includes Florida and other difficult pickup targets
Republicans are defending 22 of the 35 Senate seats up this year, along with two special election seats in Ohio and Florida.
For Democrats, winning control would still require difficult flips. CNBC said the party would need to pick up seats in states including Alaska, Texas and Ohio, even though several of the states they need were won by Donald Trump in 2024 by 10% or more.
That helps explain why prediction markets still treat the chamber as a toss-up despite the current Democratic edge.
What readers should watch next
For prediction-market watchers, the key point is that Senate control pricing remains fluid rather than settled. The next moves on Kalshi and Polymarket will likely depend on whether the current polling environment holds and how individual battleground and special election races, including Florida’s, develop closer to November.
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Source: As reported by cnbc.com.
