Congress Balance of Power: Kalshi and Polymarket Odds on Which Party Will Control Congress
Updated on 10/29/26
The Congress balance of power is the biggest question on the November 3 ballot, and the latest Congress Vegas odds on Kalshi and Polymarket agree on which party will control Congress: Democrats, and by a wide margin.
Traders on both exchanges have made a Democratic sweep of the House and Senate the clear favorite, with a Democratic House and Republican Senate as the main alternative.
Here's how the Vegas odds Congress boards on Kalshi and Polymarket stack up heading into Tuesday, November 3.
| 🏢 Platform | 🏷️ Pick | Price | 🤑 Est. Return on $100 | 📈 Trade It |
|---|---|---|---|
| Kalshi | Democrats Sweep | YES (66¢) | $151.52 | Trade it on Kalshi! |
| Kalshi | D-House, R-Senate | YES (29¢) | $344.83 | Trade it on Kalshi! |
| Kalshi | Republicans Sweep | YES (8.3¢) | $1204.82 | Trade it on Kalshi! |
| Kalshi | R-House, D-Senate | YES (0.7¢) | $14285.71 | Trade it on Kalshi! |
| Polymarket | Democrats Sweep | YES (66¢) | $151.52 | Trade it on Polymarket! |
| Polymarket | D House, R Senate | YES (28¢) | $357.14 | Trade it on Polymarket! |
| Polymarket | Republicans Sweep | YES (9¢) | $1111.11 | Trade it on Polymarket! |
| Polymarket | R House, D Senate | YES (1¢) | $10000.00 | Trade it on Polymarket! |
A full breakdown of the current Congress balance of power pricing on both exchanges follows below, but if you'd rather jump straight to the offers, grab the latest Kalshi promo code or Polymarket promo code.
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Updated on 10/29/26
Congress Balance of Power Kalshi Odds: Top Trading Contracts
Kalshi splits the Congress balance of power into four Yes-or-No contracts, one for each possible House and Senate combination. Each trades between 1¢ and 99¢, which maps directly to implied probability, so the Congress Vegas odds here read as straight probabilities, and a winning Yes share pays $1.00 while a losing share pays nothing.
House control follows the party of the Speaker and Senate control follows the party of the President Pro Tempore, with a scheduled expiration of February 1, 2027. Kalshi's rules allow earlier resolution once several designated media outlets call both chambers, and a sweep here refers only to Congress, not the presidency.
Democrats Sweep (YES 66¢)
A Democratic sweep sits at 66¢, an implied 66% chance, and Kalshi's chart shows how far it has traveled: the contract hovered around 40% for much of the summer before climbing into the mid-60s this fall.
The generic ballot is doing most of the work. The PollCheck polling average had Democrats up 8.7 points as of October 27, and a Reuters/Ipsos survey of likely voters on October 26 showed them ahead 53% to 44%.
D-House, R-Senate (YES 29¢)
This is the market's hedge on the Senate. It pays if Democrats flip the House but Republicans keep a Senate they now hold 53-47, and at 29¢ the board gives that roughly a 3-in-10 chance.
Democrats need a net gain of four seats for a 51-seat majority, because a 50-50 Senate goes to the party holding the vice presidency, which is currently Republican under JD Vance. Cook Political Report's October 6 update listed Alaska, Iowa, Kansas, Maine, Michigan, Ohio and Texas as toss-ups, so Republicans can hold the chamber by winning a handful of them.
Republicans Sweep (YES 8.3¢)
Republicans sweep has slid to 8.3¢, down from a spring peak near 27% on Kalshi's chart. History is the main headwind: the president's party has lost an average of 27 House seats and three Senate seats in midterms from 1934 to 2022, according to the American Presidency Project.
Sabato's Crystal Ball had 214 House seats rated safe, likely or lean Democratic as of October 8, just four short of the 218 needed before a single toss-up is counted.
R-House, D-Senate (YES 0.7¢)
The long shot on the board is also its least coherent outcome. A national environment strong enough to hand Democrats the Senate would almost certainly flip the House first, which is why Kalshi's tenth-of-a-cent pricing treats this combination as close to impossible.
Updated on 10/29/26
Congress Vegas Odds on Polymarket: Which Party Will Control Congress?
Polymarket's 2026 Midterms: Balance of Power board uses the same four combinations, priced between 1¢ and 99¢, so the Congress Vegas odds there are directly comparable. A Yes share pays $1.00 if the outcome hits and nothing if it doesn't, and positions can be sold at the market price before resolution.
The market closes at 11:59 p.m. ET on November 3. Senate control goes to the party with a majority of voting seats, a 50-50 split goes to the party holding the vice presidency, and House ties go to the party of the first Speaker elected, with independents counted toward the party they caucus with.
Democrats Sweep (YES 66¢)
Polymarket matches Kalshi at 66¢ on a Democratic sweep, and its chart tells the same story from a different starting point: the contract opened near 50% when the market launched in mid-August and has spent most of October between roughly 62% and 65%.
A brief spike toward 69% in late October has faded, leaving the board a few points below that peak.
D House, R Senate (YES 28¢)
The split-Congress outcome has lost the most ground on Polymarket, sliding from the low 40s in September to 28¢ now, with a dip to the mid-20s along the way.
Decision Desk HQ's forecast as of October 18 gave Democrats a 56% chance of winning the Senate, with only Iowa leaning Republican among its four toss-ups. A board that implies about 67% for a Democratic Senate is more bullish than at least one major model.
Republicans Sweep (YES 9¢)
Republicans sweep trades at 9¢, a cent above Kalshi, and it has held near 10% for most of October after sitting around 20% in early September.
For Republicans to win both chambers, they would need to keep the House despite a generic ballot that has moved toward Democrats and then survive a Senate map where Cook now rates seven races as toss-ups.
R House, D Senate (YES 1¢)
Polymarket rounds this contract to the 1¢ floor, making it the cheapest share on the board. The logic is the same as on Kalshi: the conditions that would deliver a Democratic Senate would almost certainly deliver a Democratic House too.
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Updated on 10/29/26
How Kalshi and Polymarket Compare on Vegas Odds Congress Pricing
The two exchanges are nearly interchangeable on the headline contract, with a Democratic sweep at YES 66¢ on both Kalshi and Polymarket. The split-Congress outcome shows YES 29¢ on Kalshi against YES 28¢ on Polymarket, and a Republican sweep is YES 8.3¢ against YES 9¢.
Adding the contracts together shows how little the Vegas odds Congress boards disagree. Kalshi's prices imply roughly a 95% chance of a Democratic House (66¢ plus 29¢) and about 67% for a Democratic Senate (66¢ plus 0.7¢), while Polymarket implies about 94% and 67%.
The gaps that do exist come down to precision and settlement. Kalshi quotes tenths of a cent, which is why its long-shot R-House, D-Senate contract shows YES 0.7¢ while Polymarket's board rounds to YES 1¢, and Polymarket lists a November 3 close while Kalshi schedules expiration for February 1, 2027.
Congress Balance of Power Price Analysis: Market Price Influencers
The biggest move on both boards is the Democratic sweep's climb from the 40s into the mid-60s on Kalshi, while the split-Congress contract gave back roughly a third of its September value on Polymarket. Republican scenarios have drained out of the board in tandem, with Kalshi's Republican sweep price down from a spring high near 27% to 8.3¢.
Polling explains much of that shift in the market's view of which party will control Congress. Silver Bulletin's generic ballot average had Democrats ahead by 6.6 points in early September, and the PollCheck average now shows a margin of 8.7, though the two averages are built differently and are not a like-for-like comparison.
The House looks close to decided in the Vegas odds Congress pricing, with both exchanges implying a Democratic House probability of at least 94%. The Senate is where the market is making a real judgment call, because Republicans hold a 53-47 majority and Democrats need a net gain of four seats, including wins in toss-ups such as Texas, Ohio, Maine, Iowa, Alaska and Kansas.
Cook's October 6 update moved Kansas from Lean Republican to Toss Up, New Hampshire to Lean Democrat and North Carolina to Likely Democrat, expanding the range of possible Democratic pickups to as many as six seats. Late polls and early returns from the toss-up states on Tuesday night are what could reprice the board fastest.
| 🏢 Platform | 🏷️ Pick | Price | 🤑 Est. Return on $100 | 📈 Trade It |
|---|---|---|---|
| Kalshi | Democrats Sweep | YES (66¢) | $151.52 | Trade it on Kalshi! |
| Kalshi | D-House, R-Senate | YES (29¢) | $344.83 | Trade it on Kalshi! |
| Kalshi | Republicans Sweep | YES (8.3¢) | $1204.82 | Trade it on Kalshi! |
| Kalshi | R-House, D-Senate | YES (0.7¢) | $14285.71 | Trade it on Kalshi! |
| Polymarket | Democrats Sweep | YES (66¢) | $151.52 | Trade it on Polymarket! |
| Polymarket | D House, R Senate | YES (28¢) | $357.14 | Trade it on Polymarket! |
| Polymarket | Republicans Sweep | YES (9¢) | $1111.11 | Trade it on Polymarket! |
| Polymarket | R House, D Senate | YES (1¢) | $10000.00 | Trade it on Polymarket! |
How to Trade the Congress Balance of Power on Prediction Markets
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Kalshi
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Updated on 10/29/26
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Polymarket
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Updated on 10/29/26
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Congress Vegas Odds: Final Thoughts on Which Party Will Control Congress
The Congress balance of power market has settled into a clear shape: a near-lock on a Democratic House, a Senate that traders lean toward Democrats at roughly two-to-one, and a long tail of Republican outcomes priced in single digits.
Kalshi and Polymarket land within a point of each other on every contract, so the Congress Vegas odds come down to a handful of Senate toss-ups on Tuesday night, and the answer on which party will control Congress hinges on them. If Democrats take Texas, Ohio, Maine and enough of the rest, the sweep pays; if Republicans hold even a few, the split-Congress contract is the one to watch.
Congress Balance of Power FAQs
What are the current Congress balance of power odds?
Kalshi prices a Democratic sweep at 66¢, a Democratic House with a Republican Senate at 29¢, a Republican sweep at 8.3¢ and a Republican House with a Democratic Senate at 0.7¢. Polymarket shows 66¢, 28¢, 9¢ and 1¢ for the same four outcomes.
Which party will control Congress according to prediction markets?
Prediction markets favor Democrats, and the Vegas odds Congress boards imply about a 94% to 95% chance of a Democratic House and roughly a 67% chance of a Democratic Senate on both exchanges.
What do the Vegas odds Congress boards say about a split Congress?
A Democratic House with a Republican Senate is the second most likely outcome at 29¢ on Kalshi and 28¢ on Polymarket, while a Republican House with a Democratic Senate is priced at 0.7¢ on Kalshi and 1¢ on Polymarket.
Where do the latest Congress Vegas odds come from?
They come from traders buying and selling Yes shares on Kalshi and Polymarket, so a price of 66¢ implies a 66% probability. The numbers reflect what traders are willing to pay rather than a price set by a bookmaker.
How do polls compare to the Congress balance of power market?
The PollCheck generic ballot average had Democrats up 8.7 points as of October 27, and Reuters/Ipsos showed a 53% to 44% Democratic lead on October 26, which fits a Democratic House priced at 94% or higher. The Senate is closer: Decision Desk HQ gave Democrats 56% as of October 18, below the roughly 67% the markets imply.
How do Kalshi and Polymarket differ on the Congress balance of power?
Their prices sit within a point of each other on every contract. Kalshi quotes tenths of a cent and schedules expiration for February 1, 2027, while Polymarket rounds to whole cents and lists a November 3 close.
What could change the Congress balance of power odds before Election Day?
Late polling, rating changes in the Senate toss-ups such as Texas, Ohio, Maine, Iowa, Alaska and Kansas, and early returns on Tuesday night could all move the board on which party will control Congress. The Senate contracts are the most likely to reprice because Democrats need a net gain of four seats.
How do Kalshi and Polymarket decide which party will control Congress?
Kalshi uses the party of the Speaker for the House and the President Pro Tempore for the Senate. Polymarket gives control to the party with a majority of voting seats, and a 50-50 Senate goes to the party holding the vice presidency.
How do I trade the Congress balance of power?
Sign up on Kalshi or Polymarket, fund your account, and buy a Yes share on the House and Senate combination you want, then hold it to resolution or sell it back to the market before it closes.
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