Prediction market traders expect Dems to record Blue sweep in US House-Senate
With the balance of power on Capitol Hill at stake, numerous political leaders across the US have declared Tuesday’s midterm elections to be the most critical in recent memory.
Ahead of Election Night, the Democratic Party had a strong chance to regain control of the Senate on the nation’s largest prediction-market sites. As of 9am ET, the Democrats had a 75% chance to sweep the Senate and the House of Representatives on Kalshi. Another option, a win by the Democrats in the House and a Republican victory in The Senate, had odds of just 20%. At the time, the contract received notional volume in excess of $107.8 million.
The odds fairly track trader sentiment on two other prominent sites – Polymarket and DraftKings Predictions. On Polymarket’s US platform, traders also expect a Blue sweep, with a 77% probability of a Democratic win in the Senate. Traders on Polymarket’s offshore site placed the odds slightly higher, at 78% to be precise.
On Monday afternoon, traders on DraftKings Predictions gave the party a 76% chance to control at least 51 seats, the amount needed to regain the chamber. Traders on Monday at an oversubscribed market on DraftKings placed the odds of a Republican victory at roughly 27%. The Democrats are widely expected to regain the House, with odds at major prediction markets, far above 90%.
Trigger events
The rapid proliferation of trading on election contracts represented a hot topic at two major prediction market conferences in the last month — Predict 2026 and NEXTPredict. At the latter, held at Hudson Yards in Manhattan, former Meet The Press moderator Chuck Todd cautioned that retail traders could get walloped on Election Night if the inexperienced traders did not closely follow exit polling in real time.
Another popular subject at the conference surrounded the growing popularity of “multi-step conditional contracts.” Before a contract is settled, the derivative requires a specific prerequisite or a “trigger event,” for the contract to be valid. For Election Night, Polymarket is offering several conditional contracts based upon a Democratic sweep.
One option gives traders the opportunity to place a stake on whether a Democratic candidate will win the 2028 US Presidential Election if the party records a sweep in Congress. As of Tuesday morning, the odds on Polymarket stood at 73%.
Trades on economic and geopolitical issues are also popular on the site. With the activation of the trigger event, traders anticipate a 35% chance of a US recession by the end of 2027. Traders also predict a minute chance that a US-Iran ceasefire will last through 2027, with the odds of the conditional contract at only 3%.
Close races are expected in the Senate in at least four Midwest states — Michigan, Ohio, Kansas and Iowa. As a result, there appears to be a strong likelihood that so-called Senate control contracts will not be settled on Wednesday morning.
Overall, volume on US prediction markets has increased drastically from midterms two years ago. As of Tuesday morning, notional volume on the midterms across all operators eclipsed $1.48 billion.