As voters cast their ballots during the final hours of Election Day, major prediction markets heavily favored Democrats to secure full control of both chambers of Congress.

Shortly after 6:30 p.m. EST, Kalshi priced the probability of a complete Democratic sweep—capturing both the House and the Senate—at 82%, while Polymarket pegged the likelihood slightly higher at 85%.

Both platforms indicated comparable probabilities for Democrats maintaining or winning the Senate, while expectations for capturing the House were even higher. Polymarket estimated a 97% chance of a House flip, with Kalshi trailing closely at 96%.

Entering the midterms under previous Republican control of both chambers, Democrats needed to net four seats to seize the Senate and just three to claim the House.

Financial backing in these markets reached substantial figures, with bettors wagering over $115 million on Kalshi’s congressional balance of power market, alongside more than $65 million committed to Polymarket.

Democrats Favored In Top Senate Races

Heading into the election, the Cook Political Report classified six Senate seats as pure toss-ups, all previously held by Republicans. Final polling indicated Democratic leads across each of these competitive contests. The Election Betting Odds tracker, which aggregates data from major wagering platforms, reflected this momentum shortly after 6:30 p.m. EST:

  • Alaska: Democrat Mary Peltola (73%)
  • Iowa: Democrat Josh Turek (61%)
  • Kansas: Democrat Adam Hamilton (74%)
  • Maine: Democrat Troy Jackson (73%)
  • Ohio: Democrat Sherrod Brown (82%)
  • Texas: Democrat James Talarico (80%)

Interestingly, Polymarket’s Balance of Power 2026 Midterms proposition showed the highest trading volume on the long-shot Republican Sweep outcome by early Tuesday evening. Users funneled $23.2 million into the Republican sweep prediction despite its low statistical probability, whereas the heavily favored Democratic sweep attracted $16.2 million in volume.

What Are The Odds California’s One-Time Billionaire Tax Passes?

California Proposition 40 introduced a proposal for a one-time 5% wealth tax targeting individuals and trusts possessing assets exceeding $1 billion. Shortly after 6:30 p.m. EST, Polymarket assigned a 26% probability of passage, drawing $4.6 million in total user volume, though potential legal hurdles could render the tax moot even if approved by voters.

Sentiment Tracking And Political Context

Sentiment-based platforms without financial wagering similarly reflected strong Democratic advantages, showing an 85% probability for a Senate majority and an 83% chance of controlling the House.

These midterms unfolded against a backdrop where President Donald Trump maintained an approval rating dipping below 40%. An Associated Press-NORC Center for Public Affairs Research survey revealed that roughly 80% of voters prioritized the economy and the cost of living. Democrats centered their platform on affordability amid surging grocery, fuel, and energy expenses, while Trump frequently dismissed the emphasis on affordability as a fake narrative. Furthermore, political pressure mounted over the prolonged Iran conflict; initiated after strikes in February with an anticipated duration of a few weeks, the war dragged on for eight months without a diplomatic breakthrough.

Notably, before the commencement of the conflict with Iran, the likelihood of a Democratic sweep traded below 40% on Kalshi.