House Flip? Senate Hold? Prediction Markets Unleash Wild 2026 Midterm Election Bets

Prediction market traders on Polymarket and Kalshi are pricing in a Democratic takeover of the U.S. House in the 2026 midterms while giving Republicans the edge to hold the Senate, with tens of millions of dollars wagered across hundreds of individual races and primary markets.

Ballot measures are also drawing money. California’s proposed one-time wealth tax on billionaires sits at 34% odds to pass, with $4 million traded. Michigan’s push to rewrite its state constitution is priced at just 19% odds on $6,400 in volume. In Missouri, a ban on abortion and gender transition care for minors is trading at 18% odds to pass. Nevada’s abortion protection amendment is the strongest favorite among the ballot measures, with bettors pricing a 92% chance of passage.

Texas and Alaska Senate seats are drawing close bets. Ken Paxton holds a 56% edge over James Talarico in the Texas matchup, a race Polymarket prices as a 50-50 toss-up at the party level on $611,000 in volume. In Alaska, Democrat Mary Peltola leads Republican Dan Sullivan 60% to 42%, with the seat rated lean Democrat on $367,000 traded.

Beyond the marquee contests, Polymarket has built out a full state-by-state Senate map covering 24 individual races. Republicans are treated as near locks in Nebraska, Montana, Tennessee, and Mississippi, each trading above 90%. Democrats hold similarly safe positions in Colorado, Minnesota, New Jersey, and New Mexico, all above 94%. Toss-up markets have formed in Ohio, Illinois, and Kentucky, each trading at 50% with lighter volume than the headline races.

Iowa leans Republican at 62%, while Michigan and North Carolina lean Democrat at 68% and 87% respectively, with North Carolina’s market built around Roy Cooper’s bid against Michael Whatley. South Carolina and Kansas both lean Republican in the 83% range, and states like Florida, Idaho, Oklahoma, and Louisiana sit above 86% for the GOP with comparatively thin trading volume under $60,000 apiece.

Governor’s races round out Polymarket’s midterm slate. Xavier Becerra is favored at 93% over Steve Hilton in California. New York and Maine both show Democrats above 90%, while Arizona’s Democratic candidate holds a 78% edge. Wisconsin and Georgia sit closer to even, with Democrats favored at 57% and 56%, respectively. Vermont is the lone Republican leaning governor’s race among the states listed, with the GOP favored at 83%, and South Dakota and New Hampshire also lean Republican at 93% and 79%.

On the Republican side, Florida’s 6th District primary between Randy Fine and Dan Bilzerian favors Fine at 96%, and Alabama Representative Jerry Carl is priced at 99% to turn back a primary challenge. Florida’s 2nd District primary remains the most contested Republican matchup tracked, with Keith Gross narrowly favored over Evan Power at 50% to 33%.

Illinois’ 9th District primary pitting Daniel Biss against Kat Abughazaleh has drawn $1.1 million, while Texas Representative Colin Allred’s primary against Julie Johnson in the 33rd District has traded $844,000. Michigan’s Democratic Senate primary between Abdul El-Sayed and Haley Stevens has drawn nearly $3 million, with El-Sayed favored at 79%, and Illinois’ Democratic Senate primary between Juliana Stratton and Raja Krishnamoorthi has traded $1.5 million.

Gubernatorial primaries are pulling comparable money. Wisconsin’s Democratic primary between Francesca Hong and David Crowley has drawn $1.9 million, with Hong favored at 77%. Colorado’s Republican primary between Victor Marx and Barbara Kirkmeyer has traded $1.4 million, and South Dakota’s Republican primary between incumbent Larry Rhoden and Toby Doeden has pulled in $1.3 million, with Rhoden favored at 94%. Oklahoma’s Republican primary between Mike Mazzei and Gentner Drummond has drawn over $900,000, alongside a similarly sized market in Maine’s Democratic primary between Hannah Pingree and Nirav Shah.

Kalshi traders are also pricing broader structural questions about the primary cycle. A market asking how many House Democrats will lose their primary shows 82% odds that seven or more incumbents fall, on $93,655 traded. A parallel market on House Republican losses shows 45% odds for four seats lost. A separate market tracking whether progressive Democrats sweep contested Senate primaries sits at 54% odds to complete the sweep.

Taken together, the two platforms show traders treating House control as close to settled while keeping the Senate and dozens of primary contests genuinely contested. Southern Senate and governor primaries in Texas, Kentucky, California and Florida account for more than $70 million of Kalshi’s total volume, according to the platform’s own market data, making them the dominant liquidity drivers of the 2026 midterm cycle so far.