House control odds: Democrats are about 93.5% to win the House, and the seat market expects around 240 seats
Kalshi and Polymarket both put Democratic control of the House at about 93.5% going into the final weekend, up from 77% at the end of May. The odds and how they moved, what the seat-count market expects, the redistricting fights behind the map, how big a majority looks likely, and what a 6–7% Republican chance really means.
In this article
Democrats go into the final weekend of the 2026 campaign as heavy favourites to win the House. At Friday's close, 30 October 2026, Kalshi priced Democratic control at 93.6% and Polymarket at 93.5%. Republicans, who won the chamber 220–215 in 2024, were at about 6.5%.
Kalshi's seat-count market goes further: its single most likely outcome is more than 249 Democratic seats, and the market's average works out to about 240. That would be the largest Democratic House majority since 2008.
House control odds at a glance
Source: Kalshi market data (CONTROLH-2026, KXDHOUSESEATS-27), daily close; Polymarket price history, 4 p.m. ET
Follow the live markets: House control on Kalshi, House control on Polymarket and the Kalshi seat-count market.
How the odds moved
Source: Kalshi market data: CONTROLH-2026-D, daily candles
Show the dataHide the data
| Democrats | |
|---|---|
| 31 May | 77% |
| 15 Jun | 76% |
| 1 Jul | 82% |
| 15 Jul | 82% |
| 1 Aug | 84% |
| 15 Aug | 86% |
| 1 Sep | 85% |
| 15 Sep | 86% |
| 1 Oct | 91.5% |
| 15 Oct | 90.1% |
| 30 Oct | 93.6% |
The House market has been a Democratic market all year; it just got more confident. Democrats were already a 77% favourite at the end of May, rose into the mid-80s over the summer, and crossed 90% at the start of October. The last step, to 93–94%, came this week, alongside the Senate market's move to 71% (the Senate's final week).
The Senate has been the more volatile market because it depends on a handful of close states. The House depends on hundreds of districts at once, so one poll or one candidate rarely moves it much.
How many seats?
Kalshi's seat-count market splits the possible outcomes into four-seat buckets. At Friday's close:
Source: Kalshi market data: KXDHOUSESEATS-27, daily close. The <218 bar combines three buckets. The buckets sum to slightly more than 100%.
Show the dataHide the data
| Value | |
|---|---|
| <218 | 7% |
| 218–221 | 3% |
| 222–225 | 4% |
| 226–229 | 6% |
| 230–233 | 9% |
| 234–237 | 12% |
| 238–241 | 13% |
| 242–245 | 14% |
| 246–249 | 9% |
| 250+ | 28% |
Three things stand out:
- The middle of the distribution is around 238–241 seats. Half the probability lies below that bucket and half above it.
- The top bucket is the single most likely. "More than 249 seats" is priced at 28%, up from 15% at the end of September. That reflects traders' belief that a wave, once it starts, tends to be bigger than the polls show.
- A narrow Democratic majority is unlikely. Fewer than 226 seats, a majority of a handful, is priced at about 7%. Most of the Republican chance is in outright defeat for Democrats rather than a squeaker.
Two weeks ago, the same market was centred on 234–237 seats. The shift this month has been towards a bigger majority, not just a safer one.
The map Democrats are running on
The 2026 House map is not the 2024 map. Several states redrew their districts in the middle of the decade, an unusual move that started in 2025:
- Texas redrew its map to target several Democratic-held seats, aiming to gain as many as five Republican seats.
- California answered with Proposition 50, approved by voters in November 2025, which lets the state use a map drawn to gain Democratic seats.
- Missouri and North Carolina passed new maps aimed at one additional Republican seat each.
- Ohio adopted a new map, and a court-ordered map in Utah created a district centred on Salt Lake City that leans Democratic.
On paper, the Republican-led redraws added more potential seats than the Democratic ones. That they are not enough to keep the House competitive in the markets shows how much the national environment has moved. A party drawing seats it expects to win by five points loses them when the national tide is bigger than five points. Our 2026 midterm predictions cover the redistricting battlefield seat by seat.
Kalshi vs Polymarket
| Kalshi | Polymarket | |
|---|---|---|
| Democrats win the House (30 Oct) | 93.6% | 93.5% |
| Democrats win the House (16 Oct) | 90.1% | 90.5% |
| Volume | about 86 million contracts | tens of millions of dollars |
Sources: Kalshi and Polymarket public market data.
The two exchanges have tracked each other within about half a point all month, which is what you would expect in one of the deepest markets either runs. Kalshi's House market had traded about 86 million contracts by Friday, about 70% of them on the Republican side, where each contract costs about 6 cents.
How the seat market has moved
| Democratic seats | 30 Sep | 16 Oct | 30 Oct |
|---|---|---|---|
| Fewer than 218 | 11% | 10% | 7% |
| 218–229 | 26% | 24% | 13% |
| 230–241 | 41% | 48% | 34% |
| 242–249 | 18% | 16% | 23% |
| 250 or more | 15% | 12% | 28% |
Kalshi KXDHOUSESEATS-27 bucket prices, grouped; columns may not sum to exactly 100%. Source: Kalshi public market data.
Most of the change came in the last two weeks: the middle of the distribution thinned out and the top bucket more than doubled. The market's average rose from about 234 seats in mid-October to about 240.
How to trade the House markets
The control market and the seat market answer different questions. At 93–94 cents, a Democratic control contract pays about 7% if Democrats win, which only makes sense if you think the true chance is higher still. The seat-count buckets pay more for more specific views: "250 or more" at about 28 cents pays roughly three and a half times the stake if the wave is as big as the most bullish traders expect. A Republican control contract at about 6–7 cents pays about fifteen times the stake. Each is a bet on a different shape of election night. How to size positions like these: the Kelly criterion.
What 93.5% means
A 93.5% favourite still loses about one time in fifteen. For Republicans to keep the House, one or more of these would probably have to happen:
- A systematic polling miss in Republicans' favour, like the one in several states in 2016 and 2020.
- Turnout that looks more like a presidential year among Republican-leaning voters, who turned out heavily for Trump in 2024 but are less reliable in midterms.
- The redrawn maps working better than expected, holding Republican seats in Texas and elsewhere that the national environment says should be at risk.
The seat-count market prices all of these together. Its probability below 218 seats, about 7% after accounting for the buckets summing to slightly more than 100%, matches the control market almost exactly, which is a good sign that the two markets are pricing the same picture.
Midterm history
The party that holds the White House has lost House seats in almost every midterm since the Second World War. The big losses came when the president was unpopular: Democrats lost 63 seats in 2010, and Republicans 41 in 2018. In 2022, Republicans gained only nine seats despite expectations of a wave.
| Midterm | President's party | Seat change |
|---|---|---|
| 2006 | Republican | Democrats gained 31 |
| 2010 | Democratic | Republicans gained 63 |
| 2014 | Democratic | Republicans gained 13 |
| 2018 | Republican | Democrats gained 41 |
| 2022 | Democratic | Republicans gained 9 |
A Democratic House of about 240 seats would mean a gain of about 25, a large but not historic swing, and well within the range of past midterms under an unpopular president. For how the market reads Trump's standing, see Trump approval rating odds.
Where the House will be decided
The House is decided district by district, but a few groups of seats will tell the story early on election night:
- Redrawn Texas seats. If Democrats hold the districts Texas Republicans targeted with their new map, a large majority becomes likely.
- California's new map. Proposition 50 put several Republican-held seats in play. California counts slowly, so these may not be called for days.
- Suburban seats in the Northeast and Midwest. Districts around Philadelphia, New York, Detroit and Chicago swing with the national suburban mood.
- Rural Democratic seats. A handful of Democrats hold seats Trump won comfortably. If they survive, the Republican path to a majority is very narrow.
The seat-count market should move fastest on the first group: an early Democratic hold in a targeted Texas seat would push the top buckets up within minutes, and an early Republican gain there would do the opposite.
When we will know
Most House races are called on election night or the morning after. The closest ones, particularly in California, where ballots postmarked by Election Day can arrive a week later, can take much longer. The control market could be clear on Tuesday night even if dozens of individual seats are not. Our guide to election day 2026 covers poll-closing times state by state, and when races get called explains the timing.
Key points
- Odds: Democrats 93.6% on Kalshi and 93.5% on Polymarket to win the House (30 October 2026).
- Trend: up from 77% at the end of May and about 90% in mid-October.
- Seats: the market's average is about 240 Democratic seats; "250 or more" is the most likely bucket at 28%.
- Map: mid-decade redistricting in Texas, California, Missouri, North Carolina, Ohio and Utah changed the battlefield.
- Republican chance: about 6.5%, most of it in an outright Republican hold.
FAQ
Who is favoured to win the House in 2026? Democrats, at about 93.5% on both Kalshi and Polymarket on 30 October 2026.
How many seats do Democrats need? 218 for a majority. Republicans won 220 seats in 2024.
How many seats will Democrats win? Kalshi's seat-count market points to about 240, with "250 or more" the single most likely bucket.
Can I bet on the number of House seats? Yes. Kalshi lists a seat-count market in four-seat buckets, and both exchanges list control markets (election betting odds).
What happens to my contract if the result is disputed? Both exchanges settle on official results under their rules, which can mean waiting for certification in a very close outcome.
What is the biggest House majority in recent years? Democrats won 257 seats in 2008, the largest majority of the past two decades; the Republican high since then was 247 seats in 2014. The seat market's top bucket, 250 or more, would put 2026 in that company.
Do Kalshi and Polymarket agree on the House? Yes. The two have been within about half a point of each other all month, which is typical for one of the deepest markets either exchange runs.
Prices change constantly; figures are Friday closes on 30 October 2026 unless stated. Sources: Kalshi and Polymarket public market data; US House election results. Not investment advice.
