As of September 9, 2026, Republican Party is favored in the Which Party Wins the Senate in 2026? market, at an implied probability of about 52% (52¢ per contract on Kalshi). Live prices below are pulled directly from Kalshi and Polymarket.
Kalshi vs Polymarket: 2026 Senate Control Odds
The same outcome often trades at different prices on different exchanges. The platforms currently disagree most on Democratic Party: 47% on Kalshi vs 52% on Polymarket — gaps like this are where price-sensitive traders shop between venues.
| Outcome | Kalshi | Polymarket | Gap |
|---|---|---|---|
| Republican Party | 52% | 48% | 3.5 pts |
| Democratic Party | 47% | 52% | 5.5 pts |
2026 Senate Control Odds on Kalshi
| Outcome | Implied probability | Price | Bid / Ask |
|---|---|---|---|
| Republican Party | 52% | 52¢ | 52¢ / 53¢ |
| Democratic Party | 47% | 47¢ | 47¢ / 48¢ |
2026 Senate Control Odds on Polymarket
| Outcome | Implied probability | Price | Bid / Ask |
|---|---|---|---|
| Democratic Party | 52% | 52¢ | 52¢ / 53¢ |
| Republican Party | 48% | 48¢ | 48¢ / 49¢ |
Where 2026 Senate Control Odds Have Been
Republican Party last closed at 48% (Sep 9, 2026). That is -6 points since Aug 11, 2026 (55%). Since Jul 19, 2025, the earliest daily price we track for this market, it has moved -7 points from 55%.
| Date | Polymarket | Kalshi |
|---|---|---|
| Jul 19, 2025 | 55% | — |
| Oct 7, 2025 | 74% | — |
| Dec 26, 2025 | 66% | — |
| Mar 16, 2026 | 50% | 49% |
| Jun 21, 2026 | 56% | 58% |
| Sep 9, 2026 | 48% | 53% |
Across that period the market ranged from a low of 45% on Apr 18, 2026 to a high of 75% on Oct 26, 2025. Prices are daily closes from Polymarket.
Market Odds vs Polls
Polls measure who people say they support; prediction market odds measure where traders put real money. Polling averages update every few days or weeks, while market prices react to news within minutes — including primary results, debate moments, and fundraising reports. Markets also price primary races and nominee fields before pollsters survey them. Neither is infallible: polls carry sampling error, and thin markets can be moved by a few large trades. Historically, market prices in aggregate have been well-calibrated — a 70% favorite wins about 70% of the time.
What It Takes to Flip Congress in 2026
As of August 2026, Republicans hold the Senate 53–47, and 35 seats are up in the 2026 midterms — 23 of them currently held by Republicans. Democrats need a net gain of four Senate seats to take control in 2027. In the House, Republicans hold a 218–214 edge with three vacancies, so Democrats need a net gain of three districts to flip the chamber — meaning either chamber could flip on a small number of close races. The markets above translate all of that uncertainty into live probabilities.
About This Market
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. If no party wins a majority of voting seats, the party that wins control of the chamber is the party that wins half of the voting seats and holds the Vice Presidency. If the…
How to Trade This Market
Kalshi (CFTC-regulated, all 50 states for political markets) and Polymarket (lowest fees, iOS in 49 states) both offer event markets; see our head-to-head comparison or run your trade through the fee calculator before placing it. New to event contracts? Start with how prediction markets work.
More 2026 Midterms Odds
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Common Questions
Who is favored to win the Which Party Wins the Senate in 2026? market?
As of September 9, 2026, Republican Party is favored, at an implied probability of about 52% (a 52¢ contract on Kalshi). Prices move constantly as traders buy and sell; the tables on this page show the latest synced prices.
Where can I trade the 2026 Senate Control market?
This market trades on both Kalshi and Polymarket. Kalshi is a CFTC-regulated exchange available in all 50 states for political markets; Polymarket US is open to iOS users in 49 states. See our platform reviews for fees and details.
How do prediction market odds work?
Contracts pay $1 if the outcome happens and $0 if it does not, so the price is the market’s implied probability: a 62¢ contract means traders collectively price a 62% chance. Odds come from real money changing hands, not from polls or pundits.
Prices synced September 9, 2026 from public Kalshi and Polymarket market data by Arthur Angelo. Odds move constantly; check the exchange for execution prices. This page is informational — not investment advice. PredictionScout may earn commissions from platform links; see our affiliate disclosure. More markets: all live odds pages.