2026 Midterm Election Odds: Live Prediction Market Prices

Polymarket's traders give Democrats a 72% chance of winning the Senate and 95% of winning the House in the November 3, 2026 midterms. If every race goes to its favourite, the Senate splits 53–47, and the race that decides the majority is Texas.

How to Read Midterm Election Odds

Every price on Polymarket is a probability. A Democratic Senate share trading at 67¢ pays $1 if Democrats win the Senate, so the market gives them a 67% chance. That’s decimal odds of 1.49 or American odds of −203. The other side, Republicans at 33¢, is decimal 3.03 or +203.

There’s no bookmaker in the middle. Prices are set by traders buying and selling, and Polymarket’s election markets charge no trading fee, so both sides add up to about 100%. A sportsbook’s election odds typically add up to more, which is its margin.

The Senate: Why One State Decides It

The Senate chart above lines up all 100 seats from most Democratic to most Republican. Democrats start with 34 seats that aren’t on the ballot and Republicans with 31. That leaves 35 races, and Democrats need 17 of them for a 51-seat majority.

Sort the 35 races from the Democrats’ safest to their longest shot, and the 17th is the tipping-point race: if Democrats win it, they’ve almost certainly won every race they’re more likely to win, too. That’s why the Senate control price tends to sit close to the tipping-point state’s price. When they drift apart, the market is telling you something: that the races are likely to move together, or that one race is mispriced.

Races don’t move independently. A national swing of a few points pushes every competitive race the same way, which is why the seat-count market spreads its chances wider than adding up the individual races would suggest.

The House

All 435 seats are up, and 218 wins the majority. There are too many House races to list here, so the House is best read through two markets: the control market and the seat-count market, which shows how big a majority the market expects. New congressional maps in several states, drawn since 2024, make the seat count harder to call than usual.

Trading the Midterms on Election Night

I do a lot of market making on politics, mostly on smaller elections around the world, where the order books are thin and need someone quoting both sides. US elections are different: they’re so liquid they don’t really need market makers. That liquidity is there in the run-up and on the night itself.

On election night the markets are one of the best ways to follow the count. Everyone trading has money on the line, so the price is an honest read of what’s happening as results come in. Prices often move on TV network calls, but the market puts each call in context: traders weigh the calls and updates from different networks by how much they trust each one. And some markets stay open for days while the last votes are counted.

Two things to watch if you trade on the night:

• Spreads. The biggest markets stay deep, but smaller races can thin out when news breaks. Use a limit order rather than paying whatever is on the book.
• Rules. Each market resolves on its own terms. Read the rules before you trade: a party market counts independents for neither side, and runoffs count as part of the race.

How Polymarket’s Midterm Markets Resolve

• Senate control goes to the party that wins a majority of voting seats. A 50–50 Senate goes to the party of the Vice President.
• House control goes to the party with a majority of seats. If no party has one, it goes to the party of the first Speaker the new House elects.
• Race markets pay out on the winner of that race, including any runoff.

Results in close races, ranked-choice states and runoffs can take days or weeks. You don’t have to wait: you can sell your shares at the market price any time before the market settles.

Getting Started

Create a Polymarket account here to trade the midterm markets. Polymarket’s availability depends on where you live, so check your country first.

• What is Polymarket?: how prediction markets work
• How markets resolve: who decides the outcome, and disputes
• Odds converter: turn any price into decimal, fractional or American odds
• Futures odds: live Polymarket prices on sports title markets