Democrats Command 78% Senate Odds Amid $1.9B in Election Bets

Prediction market traders have wagered $1.9 billion on the 2026 midterm elections as of 8 p.m. ET on Monday, Nov. 2. The funds split across two major platforms, with Kalshi accounting for $1.3 billion in trades and Polymarket handling $600 million, according to a Washington Post analysis.

The current odds heavily favor Democratic candidates for control of Congress. Polymarket assigns a 78% probability to Democrats winning the Senate and a 95% probability to them flipping the House. Kalshi mirrors the Senate odds at 78% but sets the House flipping probability slightly lower at 93.9%.

These platforms function by allowing users to buy and sell contracts on specific race outcomes. Both Kalshi and Polymarket ban insider trading. Kalshi defines the rule as trading while possessing information that materially affects the decision to trade. Polymarket has investigated dozens of recent midterm-related trades for insider trading and manipulation, a move reported by NPR.

The $1.9 billion in election betting sits against a larger backdrop of campaign spending. Candidates are expected to spend $3.9 billion on advertising across House and Senate races, based on a New York Times analysis of data from media-tracking firm AdImpact.

This midterm wagering volume is lower than the previous cycle. During the 2024 presidential election, more than $3.6 billion was wagered on Polymarket alone regarding the Trump versus Harris race. In that prior contest, prediction markets signaled a Trump victory, a result that ran counter to many polls that showed Harris with a double-digit lead.