Midterm sweep odds: Dems 62% on Polymarket

Democrats are priced as favorites to win both chambers in the 2026 midterms, with sweep odds at 62% on Polymarket and 61% on Kalshi as of Oct 11, 2026, at 4:54 AM ET. Reported trading volume stands at $21.2M on Polymarket and $35.87M on Kalshi.

Markets and polling point in the same direction

The supplied Polymarket source gives a more precise implied sweep probability of 61.5%, compared with the rounded 62% headline figure. Both platforms put Democratic control of the House and Senate above an even chance, but well short of certainty.

According to Polymarket, recent polling averages place Democrats roughly seven points ahead on the generic congressional ballot. The source links that advantage to dissatisfaction with the incumbent president, whose approval rating is near 37 percent, alongside broader midterm dynamics.

Senate control remains central

Polymarket identifies Ohio, Texas, Alaska, Maine, and Michigan as competitive Senate contests where the political environment has improved Democratic prospects. According to the source, multiple models now forecast net gains sufficient for Democrats to take control of the chamber.

House forecasts are stronger still, assigning Democrats probabilities above 90 percent, according to Polymarket. The source attributes that outlook to suburban voting trends and opportunities in open seats. That contrast makes the Senate outlook particularly important to the probability of a two-chamber sweep.

Final advertising spending and turnout efforts through early November remain the principal variables that could change the outcome, according to Polymarket. The current market prices therefore reflect a Democratic advantage rather than a settled result.

What it means for prediction markets

• Cross-platform agreement: Polymarket’s headline 62% and Kalshi’s 61% indicate closely aligned sweep expectations, despite different reported trading volumes.
• The sweep is not the House alone: House forecasts above 90 percent are substantially higher than the two-chamber market price, highlighting the importance of Senate control.
• Late-campaign sensitivity: Advertising and turnout developments through early November could still shift sweep odds.