The 2026 midterm elections are 39 days away, and prediction markets are pricing one of the most divided outcomes in a decade. As of Friday’s close, traders on Kalshi give Democrats a 58% chance of capturing the Senate, while Republicans hold a 61% probability of retaining their narrow House majority. That combination, a split Congress with divided control, is now the single most-traded macro-political outcome across both major US prediction markets, with more than $47 million in combined open interest.
The story of the past week has been Democratic momentum in the Senate map colliding with entrenched Republican durability in individual House districts. Below is where the money is flowing, what markets are saying about the tossup races, and how the numbers have shifted since Labor Day.
Senate Control: Democrats Now 58% Favored
Two weeks ago, Senate control was trading as a genuine coin flip at 51/49. Today the market has moved firmly toward the Democrats. The catalysts were Republican fundraising shortfalls in North Carolina and Maine plus a late-September polling shift in Pennsylvania that showed the Democratic challenger opening a 4-point lead outside the margin of error.
The individual seat contracts tell the story most clearly. Kalshi’s most heavily traded Senate contracts as of September 25:
- Maine (Collins vs. Bellows): 54% Democratic. Susan Collins has closed some of the gap but still trails in three consecutive independent polls.
- North Carolina (open seat): 61% Democratic. The retirement of Thom Tillis reshaped this contract; Democratic candidate Jeff Jackson has led every poll since August.
- Pennsylvania: 57% Democratic. The market’s biggest weekly mover, up 9 points on the challenger.
- Ohio: 46% Democratic. The tightest true tossup left on the board.
- Georgia (Ossoff): 63% Democratic hold. Sherrod Brown-style incumbency premium.
- Michigan (open seat): 66% Democratic hold.
Republicans need a net gain of one seat to keep the chamber. The math is tighter than the headline number suggests: if Democrats sweep Maine, North Carolina, and Pennsylvania while holding all of their own seats, control changes. Markets are pricing that exact scenario at roughly 41%.
House Control: Republicans Still Favored, but the Margin Is Shrinking
The House is a different story. Despite Democratic enthusiasm, prediction markets give Republicans a 61% chance of holding the chamber, down from 68% at the start of September but well above a tossup. The reason is structural: the current Republican majority sits at 220-215, and only about 22 seats are considered truly competitive.
Polymarket’s largest House-related contracts as of Friday:
- Republicans retain House majority: 61% (down from 68% on September 1)
- Democrats win House majority: 37% (up from 30%)
- Neither party wins a majority larger than 5 seats: 71%
- House majority decided within 72 hours of Election Day: 44%
The seven-point swing toward Democrats over the past three weeks reflects two things: a small but real generic ballot shift, and California redistricting rulings that traders now expect to marginally favor Democratic candidates in two San Diego-area districts.
The Governor Races Moving the Most Money
Gubernatorial contracts have quietly become the third-largest political category on Kalshi, behind only presidential futures and Senate control. Thirty-six governor’s mansions are on ballots this November. The four most-traded races:
- Georgia: Democrat favored at 54%. Kemp is term-limited; open seat dynamics dominate.
- Nevada: Republican Lombardo favored at 59%.
- Arizona: Democrat Hobbs favored at 62% for a second term.
- Wisconsin: Democrat favored at 55% in an open seat.
The aggregate governorship count contract has Democrats picking up a net of two mansions at 48%, which would give them 25 to Republicans’ 25, an even split for the first time since 2018.
What Markets Are Ignoring That They Probably Shouldn’t Be
Two undertraded contracts stand out. First, the “House majority not called by November 5” market is sitting at 44% despite three uncalled 2024 California races that took more than a week to resolve; the fair value here likely belongs closer to 55%. Second, the “at least one incumbent Senator loses a primary before Election Day” contract has closed but expires in three weeks and is still trading at 6% on residual Kalshi liquidity, essentially free money on the No side.
Traders should also watch generic ballot spread contracts, which have widened to a 3.4-point Democratic edge on Polymarket. Historically a spread of that size correlates with a 4 to 6 seat House swing, which would be enough to flip control on its own. The market is not yet pricing that fully.
Where to Trade These Markets
Both major regulated US prediction markets carry the full slate of 2026 election contracts. Kalshi is the deeper liquidity venue for Senate and gubernatorial races, with tight spreads and CFTC-regulated cash settlement. Polymarket offers a wider range of derivative contracts including margin-of-victory and specific vote-share brackets, along with faster market creation for breaking news.
For a full comparison of every prediction market carrying 2026 election contracts, including fees, deposit methods, and available race coverage, see our 2026 Best Prediction Markets Rankings. Political markets close at the moment polls close on election night; get positioned before liquidity thins in the final week.