Odds of Democrats sweeping midterms rise above 75% on Election Day

Prediction-market traders pushed the odds of a Democratic sweep of Congress above 75% early Tuesday, when voters head to the polls for the midterm elections.

Polymarket put the probability of Democrats winning both the House and Senate at 77% in early Tuesday trading, up from about 72% on Sunday. The contract for a split Congress with a Republican Senate and Democratic House fell to 20%, while a Republican sweep stood at 6%.

Kalshi showed a similar move, with its Democratic-sweep contract around 75% in early Tuesday trading, up roughly 5 percentage points on the day. A Democratic House and Republican Senate was priced at 19%, while a Republican sweep stood at 6.4%.

The move builds on a sharp shift toward Democrats in recent weeks. Polymarket’s House market put Democratic control at about 95%, while its Senate market was around 76% early Tuesday. Kalshi likewise showed Democrats heavily favored in its House market, with the Senate contest closer.

Trading activity has also accelerated into Election Day. More than $60M had traded in Polymarket’s balance-of-power market, while Kalshi’s comparable contract had drawn more than $100M in volume.

Odds of a Dem sweep rose sharply after mid-September.

Prediction-market prices can move rapidly as traders respond to turnout reports, late polling and, later Tuesday, incoming election results. The probabilities represent a live snapshot rather than a fixed forecast.

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