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Kalshi and Polymarket agree almost exactly on the House and differ by a couple of points on the Senate. Both give Democrats about a 90% chance of winning the House and roughly 63% of winning the Senate, with 14 days to go until Election Day on 3 November.
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Here are the current prediction market odds for the 2026 midterms, how they have moved since March, how to read them, and how the markets decide who won. Prices change by the hour, so treat everything here as a dated snapshot.
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Prediction markets are not polls and not guarantees. Prices were checked on 19 October. For live numbers, see our 2026 midterm elections predictions hub.
Midterm Prediction Market Odds at a Glance
| Market | Kalshi | Polymarket |
|---|---|---|
| Democrats win the House | 90% | 91% |
| Republicans win the House | 10% | 10% |
| Democrats win the Senate | 61% to 63% | 63% to 65% |
| Republicans win the Senate | 38% to 40% | 37% |
The figures add to slightly more than 100% because prices include spreads and fees. Ranges reflect different readings on 17 to 19 October.
Who Controls Congress? The Balance of Power Market
This market prices the four possible combinations of House and Senate control. It tells a more useful story than either chamber alone.
| Outcome | Kalshi (12 Oct) | Polymarket (17 Oct) |
|---|---|---|
| Democrats win both chambers | 61% | 63% |
| Democrats win the House, Republicans keep the Senate | 30% | 28% |
| Republicans win both chambers | 11% | 9% |
| Republicans win the House, Democrats win the Senate | 1% | 1% |
Read it this way. The most likely single outcome is a Democratic sweep, and the second most likely is a divided Congress with the House flipping and the Senate staying Republican. The market sees a Republican House with a Democratic Senate as very unlikely.
How the Senate Odds Have Moved This Year
The House has been steady. The Senate has not.
| Date | Kalshi Senate odds |
|---|---|
| March 2026 | Republicans 56%, Democrats 44% |
| 14 September | Democrats move ahead for the first time, 53% to 47% |
| 15 October | Democrats 62%, Republicans 38% |
| 19 October | Democrats about 63% |
That swing came alongside polling that shows Democratic candidates competitive or narrowly ahead in several Republican-held states, including Alaska, Kansas and Texas, and alongside race-specific news. The Senate control market on Kalshi had more than $63 million traded by 15 October.
What the Numbers Do and Do Not Mean
- A price is a probability. A contract at 63 cents implies roughly a 63% chance, because it pays $1 if the outcome happens and nothing if it does not.
- It is not a poll. Polls measure what voters say now. Markets reflect what traders believe will happen, including uncertainty.
- Ninety percent is not certainty. A 10% outcome happens about once in ten tries.
- Prices can be skewed by thin trading. Control markets are heavily traded, but many individual races are not.
Why Kalshi and Polymarket Differ
The two platforms offer similar but not identical markets, and each price is set by its own traders. A gap of one to two points is normal and does not mean one platform knows something the other does not.
There is one structural difference. Polymarket runs an international book and a separate US platform, and their prices are not interchangeable. When you compare, make sure you are comparing like with like, and note which version a source is quoting.
How the Midterm Markets Settle
This matters more than most traders expect. On Kalshi, the Senate control market settles on a consensus of media organisations about which party controls the chamber. If there is no consensus, it falls back to the party of the Senate president pro tempore on 1 February 2027.
Results that look settled on election night can take time to confirm, and close races can take days. Platforms resolve from official or consensus sources, not from projections on television.
Where the Odds and the Seats Come From
- House: Republicans hold a 220 to 215 majority, and 218 seats are needed. The last three House elections were won with 222, 222 and 220 seats, so the margin is thin.
- Senate: Republicans hold 53 seats and Democrats 47. Democrats need a net gain of four seats, not three, because Vice President JD Vance would break a 50-50 tie.
For the seat-by-seat picture, see our prediction market politics guide to the Senate battlegrounds.
Prediction Markets Are Not Legal Everywhere for Elections
Roughly two dozen states prohibit election betting under existing law, and the legal fight over whether those laws apply to prediction markets is unresolved. Prediction markets are also not sportsbooks, and trading involves a real risk of loss. If you are thinking of trading, check your state first. Our guide to election betting by state explains where things stand.
Frequently Asked Questions
What are the prediction market odds for the 2026 midterms?
As of 19 October, Kalshi gives Democrats about a 90% chance of winning the House and about 63% of winning the Senate. Polymarket is within a couple of points on both.
Who is favoured to win the Senate?
Markets favour Democrats at about 61% to 65%, depending on the platform and the day. Republicans hold 53 seats and Democrats need a net gain of four.
What is the most likely outcome of the midterms?
A Democratic win of both chambers, at about 61% to 63% in the balance of power market. The next most likely is a Democratic House with a Republican Senate, at about 28% to 30%.
How accurate are prediction markets?
Platforms say their markets are well calibrated, but a favourite at 63% still loses about one time in three. Markets can be wrong, and thinly traded ones can be moved by small bets.
How do the midterm markets settle?
Kalshi settles Senate control on a consensus of media organisations, with a fallback to the president pro tempore on 1 February 2027. Results can take days to confirm.
When is the 2026 midterm election?
Tuesday 3 November 2026.
Prediction markets are not sportsbooks. Event contract trading involves significant risk and is not appropriate for everyone. You can lose your entire stake. Platforms are typically 18+ and are not available in all states, and some states prohibit betting on elections. Prices are snapshots, not predictions or guarantees. This article is informational and is not financial, legal or voting advice. GamingToday does not endorse any candidate or party. If gambling or trading stops being fun, call 1-800-GAMBLER for confidential support.
