Polymarket shows Democrats heavily favored for House, slight edge in Senate in 2026

Polymarket’s midterm election markets are painting a picture that should make Republican strategists uncomfortable. Democrats currently sit at an 88% probability to win the House and a 51% chance to flip the Senate, according to the blockchain-based prediction platform’s latest trading data. The Senate race remains genuinely competitive, with Democrats holding just a one-point edge over the implied 50/50 baseline. What the balance of power markets are saying Polymarket’s balance-of-power combination markets, which let traders bet on the composition of the entire Congress rather than individual chambers, point to a split government as the most likely outcome. A scenario where Republicans keep the Senate but Democrats take the House is priced somewhere in the 38-48% range. A full Democratic sweep of both chambers sits at roughly 33-47%. A complete Republican hold, where the GOP retains control of both the Senate and the House, lingers in the 13-18% zone. The trading volumes behind these numbers lend them some credibility. The House market alone has seen over $4-9 million in transactions, while Senate market volumes range from $2-4 million. History and the models agree, mostly Polymar...