The United States votes in its midterm elections on November 3, 2026. All 435 seats in the House of Representatives are up, along with 35 of the 100 Senate seats and governorships in 36 states. The result decides whether President Trump spends his last two years with a friendly Congress or one that can stall his bills and budgets.
Polymarket traders have already priced it. As of October 20, “Democrats win the House” trades at 91.5¢ and “Democrats win the Senate” at 64.5¢. The first looks close to settled; the second is a genuine contest. Here is how the election works, what markets it produces and when those markets show up on a Prop Hub account.
Why they’re called midterms
Presidents serve four-year terms, House members two. So halfway through every presidential term the country votes again, with no presidential race on the ballot.
Senators serve six years, and the chamber turns over in thirds: one of three “classes” is up every two years. In 2026 that’s Class II, 33 seats. Two special elections add to it: Ohio, for the seat JD Vance left to become Vice President, and Florida, for Marco Rubio’s former seat. Voters have elected senators directly since the 17th Amendment of 1913; before that, state legislatures picked them.
The midterm pattern
The president’s party nearly always loses House seats in a midterm. In the last hundred years it gained only three times: 1934, 1998 and 2002. The losses can be steep:
- 1994: Republicans gained 54 seats under Clinton and took the House for the first time in 40 years.
- 2010: Republicans gained 63 seats under Obama.
- 2018: Democrats won back the House under Trump, picking up 41 seats.
- 2022: Republicans took a narrow House majority under Biden while Democrats held the Senate.
That history is part of why the Democratic House price sits so high. The Senate is harder to call: only a third of the seats are up, and the map depends on whose seats happen to be on the ballot this cycle.
What’s at stake in 2026
| Chamber | Seats up | Needed for control | Current split |
|---|---|---|---|
| House | all 435 | 218 | 218 Republicans, 214 Democrats, plus vacancies |
| Senate | 35 of 100 | 51 (Vice President breaks a 50–50 tie) | 53 Republicans, 45 Democrats, 2 independents who caucus with Democrats |
| Governors | 36 states, 3 territories | — | 26 Republican, 24 Democratic states |
House figures are as of October 19. Democrats need a net gain of only a few House seats. The Senate is a taller order: with Vice President Vance breaking ties, Democrats need a net gain of four. Republicans are defending 22 of the 35 seats up, Democrats 13.
The same ballot carries state legislatures, attorneys general, judges and local ballot measures.
Dates, and why results can take a while
Election Day is Tuesday, November 3 — by law, the first Tuesday after the first Monday in November. Many states run early and mail voting through October.
Counting can stretch out:
- Mail ballots. California and several other states accept ballots for days after the election if they’re postmarked by Election Day.
- Runoffs. In Georgia, if no candidate passes 50%, the top two meet again four weeks later.
- Ranked-choice voting. Maine and Alaska reallocate votes by second preferences when nobody has a majority, which adds time.
In 2022 the AP didn’t call the House for Republicans until November 16, eight days after the vote. The new 120th Congress is sworn in on January 3, 2027.
Midterm markets on Polymarket
There are dozens of markets on this election. Prices are as of October 20.
- Chamber control. “Which party will win the House in 2026?” and its Senate twin. These are the biggest: the House market has traded over $18 million.
- Balance of power. Four combinations in one market: Democratic sweep 62.5¢, Democratic House with a Republican Senate 27.5¢, Republican sweep 8.5¢, and the reverse split under 1¢.
- Individual Senate races. Texas: James Talarico (D) 62.5¢, Ken Paxton (R) 37.5¢. Maine: Troy Jackson (D) 63.5¢, Susan Collins (R) 36.5¢. Ohio: Sherrod Brown (D) 63.5¢ against Jon Husted (R).
- Governors. Ohio, for instance: Amy Acton (D) 72¢, Vivek Ramaswamy (R) 28.5¢. Georgia is close to even.
- Seats and margins. Republican House seat ranges, which Senate races finish within 5% or 1%, turnout, and the national House popular-vote margin.
A price in cents is the market’s probability estimate: 64.5¢ on a Democratic Senate means roughly a 65% chance. More on reading prices this way in prices are probabilities.
How it works on Prop Hub
Prop Hub lists only markets that end within 2 days. The clock runs to the market’s end date on Polymarket, not to the event itself. Right now the main election markets end on November 4 at 04:59 UTC — midnight on November 3 in New York. They should appear in the Market tab from around the morning of November 2 and stay tradable until that cutoff. If Polymarket moves the end date, the window moves with it.
Worth knowing in advance:
- The window is short. You can buy and sell until the market’s end date. After that the position waits for the result and closes on Polymarket’s resolution, even if the count drags on for days.
- Per-outcome limit. No more than 5% of the starting balance in one outcome — $500 on a $10,000 account.
- Near-certain outcomes. Positions opened above 90¢ count on the account but not toward the withdrawable profit on a funded account. A Democratic House at 91.5¢ already falls into that zone.
To try the election without paying anything, there’s the $100 welcome account. It runs for 3 days, so opening it on November 1 or 2 covers the trading window. Paid challenges are on the plans page.
How to read chamber and race prices, and how the markets tie together, is covered in reading US midterm markets. What happens to prices while the votes are counted is in the piece on election night.