2026 midterm election odds: House and Senate
Americans vote on November 3, 2026 for all 435 House seats and about a third of the Senate. These are the prediction market odds for which party controls each chamber, side by side from Kalshi and Polymarket, with 90 days of history.
Democrats win the House
The markets
Which party will win the House?
Kalshi · 38.7M contracts traded · Polymarket · $12.6M traded
| Outcome | Kalshi | Polymarket | Average |
|---|---|---|---|
| Democrats | 91% | 92% | |
| Republicans | 8.6% | 8.5% |
Which party will win the Senate?
| Outcome | Kalshi | Polymarket | Average |
|---|---|---|---|
| Democrats | 62% | 62% | |
| Republicans | 38% | 38% |
What to know
- Base rate: the president's party has lost House seats in every midterm since World War II except two, 1998 and 2002. That history is a strong headwind for the party in the White House.
- The House is decided by all 435 seats; a majority is 218.
- The Senate depends heavily on which seats happen to be up this cycle, so national mood matters less than the map.
- Odds move on polls, special elections, retirements and campaign finance reports, and usually most sharply in the final weeks.
How these markets resolve
- Kalshi, “Which party will win the U.S. House?”: If the Democratic Party has won control of the House in 2026, then the market resolves to Yes. Full rules
- Polymarket, “Which party will win the House in 2026?”: This market will resolve according to the party that wins control of the United States House of Representatives in the 2026 United States midterm election. A party wins control of the United States House of Representatives if it wins a majority of the chamber’s voting seats. Full rules
- Kalshi, “Which party will win the U.S. Senate?”: If the Democratic Party has won control of the U.S. Senate in 2026, then the market resolves to Yes. Full rules
- Polymarket, “Which party will win the Senate in 2026?”: This market will resolve according to the party that wins control of the United States Senate in the 2026 United States midterm election. A party wins control of the United States Senate if it wins a majority of the chamber’s voting seats. Full rules
How to read these odds
A price of 30¢ on a contract that pays $1 means the market puts the event at roughly 30%. Prices move with supply and demand, include fees and spreads, and can lean on long shots. When the two markets disagree by more than a few points, check whether their rules or deadlines differ. More in how prediction markets work and the favorite-longshot bias.
FAQ
Who is favored to win the House in the 2026 midterms?
As of Sep 29, 2026, Kalshi prices it at 91% and Polymarket prices it at 92%. These are market prices, roughly the probability traders are willing to bet on, not a guarantee.
Why do Kalshi and Polymarket show different odds?
They are separate markets with different traders, fees and sometimes different rules or deadlines. A gap of a few points is normal; a large gap is worth checking against each market's rules.
How often are these odds updated?
Sikt refreshes this page from Kalshi's and Polymarket's public data several times a day. The time of the last update is shown at the top.
Are prediction market odds accurate?
Often, but not uniformly. Research on Kalshi finds prices are informative and improve as a market nears its close, but long shots tend to be overpriced (the favorite-longshot bias).
Market data from the public Kalshi and Polymarket APIs, shown for information only. Prices are midpoints or last trades and can be several hours old. Sikt Intelligence is not affiliated with Kalshi or Polymarket. Not financial or investment advice.