Polymarket traders are pricing a Democratic takeover of both chambers of Congress in the 2026 midterm elections, with significant implications for crypto legislation and regulatory oversight. As of October 20, the House market gave Democrats a 91.5% chance of winning the House and a 64.5% chance of taking the Senate. A Democratic sweep of both chambers was priced at 62.5%, a Democratic House with a Republican Senate at 27.5%, and a Republican sweep at just 8.5%.
The Senate market has moved toward Democrats over the past month, climbing from 60.5% on September 21 to 64.5%, while the House contract slipped from 92.5% to 91.5%. The balance-of-power market was the deepest at $25.54 million traded, followed by the House at $18.78 million and the Senate at $7.23 million. Because the Senate contract is the thinnest, traders note it can be moved more easily by large orders.
A Democratic House would likely make Maxine Waters the chair of the House Financial Services Committee, replacing Republican Chair French Hill. Waters previously chaired the committee from 2019 to 2023 and has pushed for tighter crypto oversight. Her path is not entirely clear, however: Representative Sean Casten is challenging her for the top Democratic spot.
The policy stakes are most visible in the CLARITY Act, a crypto market-structure bill. It passed the House 294–134 in July 2025 but failed a Senate procedural vote 49–50 on September 15. Senator Thom Tillis entered a motion to reconsider, keeping the bill alive for a lame-duck session after the election. If it expires with this Congress in January, it would restart in front of a likely Democratic House.
More broadly, prediction markets are heading into this election far larger than in 2024. Combined monthly trading volume on Kalshi and Polymarket more than doubled from $26 billion in May to $53 billion in July, according to Pew Research Center. Politics remains a smaller slice: roughly $2 billion per month on Polymarket and under $300 million on Kalshi. The CFTC withdrew a proposal that would have classed election contracts as gaming, and on June 10 proposed a structured framework for event contracts.
The NEXTPredict summit in New York on October 22–23 will test the relationship between pollsters and prediction markets. Former Meet the Press moderator Chuck Todd is scheduled to moderate a panel called Who Calls the Midterms: Polls, Models or the Markets? Traders caution that many congressional markets are thin; research shared with CNBC found that a $3,500 bet can move 97% of midterm-related markets by five cents or more.
