Senate odds diverge across Kalshi and Polymarket amid unresolved races
Action Network reports Kalshi prices Democratic Senate control at 69 percent with the House at 91 percent, while Polymarket prices Senate control closer to 73 percent. Forecaster Nate Silver runs above both venues, at 95 percent for the House and in the high 70s for the Senate, while the Cook Political Report counts seven Senate races still within the margin of error.
Democratic control of the Senate is priced at 69 percent on Kalshi and closer to 73 percent on Polymarket, according to Action Network. The figures put Polymarket roughly four percentage points above Kalshi on the same broad electoral outcome.
The report, published Nov 3, 2026 · 6:15 PM ET, also places Democratic House control at 91 percent on Kalshi—a substantially higher probability than the venue assigns to the Senate.
Silver puts Democrats above market estimates
Forecaster Nate Silver assigns Democrats a 95 percent probability of controlling the House and a Senate probability in the high 70s, according to Action Network. His Senate assessment exceeds those of both venues, while his House estimate is four percentage points above Kalshi’s.
Those comparisons reveal a gap between the reported market prices and Silver’s forecasts. The supplied figures do not establish why those assessments differ or whether the differences have grown over time.
Seven Senate races remain close
The Cook Political Report counts seven Senate races still within the margin of error, according to Action Network. That leaves a substantial group of closely contested races alongside market estimates that favor Democratic Senate control.
The contrast is important: a chamber-level probability describes the likelihood of control, not the certainty of individual race results. The reported figures favor Democrats without treating the Senate outcome as settled.
What it means for prediction markets
- Venue differences matter: Kalshi’s 69 percent Senate figure is below Polymarket’s roughly 73 percent, so neither price alone represents a uniform market assessment.
- Forecasts provide a separate benchmark: Silver’s Senate probability in the high 70s and House probability of 95 percent are higher than the corresponding market figures supplied.
- Race-level uncertainty remains: Cook’s seven Senate races within the margin of error provide context for why a favored chamber-control outcome is still uncertain.
Sources & attribution
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