2026 midterm odds: Democratic sweep firms to 68.5%

Five days before the 2026 midterms, Polymarket's most heavily traded contracts have stopped being about the race for a single chamber and become a single number: the odds of a unified Democratic Congress. The venue's 2026 Balance of Power market now prices a Democratic Senate and a Democratic House at about 68.5 percent, up from the 66.5 percent the desk recorded for a Democratic sweep on October 22. The shift is small but consistent, and it is concentrated exactly where the market thinks the real swing sits: not the House, which traders have treated as nearly settled, but the Senate.

The composite is the cleanest read because Polymarket offers it directly, as four mutually exclusive Balance of Power contracts that trade within the same order book. The Democratic Senate and Democratic House leg trades at 68.5 percent. The Republican Senate and Democratic House leg, the classic divided-government scenario, sits at 24.5 percent. The Republican Senate and Republican House sweep is down at 6.5 percent, and the inverse split, a Democratic Senate with a Republican House, prints at roughly 0.7 percent. Added together the four legs price to roughly 100 percent, a sign the ladder is internally coherent rather than a collection of drifting one-off bets.

Related reading: 2026 midterm odds: split Congress now 26.5 percent on Polymarket.

The component markets tell the same story from a different direction. Democratic control of the House is priced at 93.5 percent, with the best bid at 0.93 and best ask at 0.94. Republican control of the House is the mirror at roughly 7 percent. On the Senate side, Democratic control sits at 68.5 percent and Republican control at 31.5 percent. Because the House leg is nearly settled in the market's estimate, the probability of a unified Democratic government, 68.5 percent, tracks the Senate number almost one for one. The Senate is the swing chamber, and the composite is, in effect, a Senate call.

That concentration shows up in the trading data. The Republican-control-of-the-House contract, despite bidding near 7 cents, posted the group's largest 24-hour dollar volume at about $2.7 million as of October 30, followed by the Democratic House leg at roughly $2.1 million. Even at a 7 cent price, active two-way flow on the House tells you traders are positioning for a near-term resolution rather than parking money five days from the vote. All four chamber contracts and the four Balance of Power legs expire at 04:59 UTC on November 4, the evening of election day as counted in US time zones.

Related reading: 2026 midterm election odds: Polymarket prices a Democratic Congress sweep at 66.5 percent.

The trajectory has been gentle but has momentum behind it. The desk last read this complex on October 26, when the four-way ladder priced a split Congress at 26.5 percent, and on October 22, when a Democratic sweep printed at 66.5 percent. Today the sweep has firmed to roughly 68.5 percent while the split has eased to around 25 percent. That is not a violent repricing, but the direction of travel is notable because it came during a week when the venue itself was under stress. On October 29 Polymarket suspended trading on its international platform for roughly an hour after a third-party provider breach drained some user funds, reverting to cancel-only mode before trading resumed, according to Polymarket's status page and CNBC. The venue said affected users would be made whole, and its US platform was not affected. The congress contracts were live again on the order book this morning, and the composite held its level through that episode.

The market's conviction, however, is not uniform, and the risk sits mainly on one side of the ladder. The House leg at 93.5 percent leaves just 6.5 percent of probability that a political shock reorders the lower chamber in the final five days, a thin cushion for a market that has been wrong about the House before. The Senate, where the spread is real, is where a surprise would land. A Republican Senate win paired with a Democratic House, the divided outcome priced near 25 percent, would deny a unified agenda even if the House stacks for the majority, and that scenario is where the residual uncertainty is being sold at a discount. For a reader watching these numbers as expectations rather than certainties, the honest summary is that the market regards a Democratic sweep as the base case at roughly two to one, while it continues to keep about a quarter of the probability on divided government.

Related reading: Fed December 2026 hike odds: Polymarket prices 74.5% for a 25 bps move after jobless claims print at 194,000.

The reading is a market expectation, not a prediction of a specific outcome. Congress-control contracts are binary by construction, and they resolve to binary settlements after the results are certified, so the 68.5 percent price is best understood as the crowd's current estimate of the probability of that specific outcome, not as a statement about any candidate or party beyond what the contracts themselves encode. Election markets are frequently most informative about how the tail of an unexpected sweep or split is being priced, which is exactly the information the four-way Balance of Power ladder carries better than any single chamber market does.

What to watch between now and the November 4 close is whether the Senate leg keeps leading the composite or whether the House leg starts to give back some of its 93.5 percent. A divergence between the Balance of Power composite and its components would be the signal that the ladder is coming under strain, and that is the first thing this desk will check once the print is out. The next scheduled inputs are the final pre-election polls in the battleground states that decide the Senate, which land in the next few days, and then the certification window after the polls close.

Related reading: Fed rate hike odds: 86.5% hold vs 54% hike; who's right.

Resolutions

Federal Reserve October 2026 decision. The Polymarket October Fed-decision market resolved to the no-change outcome on the October 28 FOMC decision. The Federal Open Market Committee held the federal funds target range at 3-3/4 to 4 percent by a 10 to 2 vote, per the Federal Reserve's October 28 statement. When the desk covered this market on October 23 it priced the holding path at 91.5 percent, and the contract settled as expected.

This content is for informational purposes only and does not constitute financial advice. Past performance is not indicative of future results. Consult a qualified financial advisor before making investment decisions. Market odds analyzed here are expectations derived from prediction-market pricing; they are not recommendations to buy or sell any contract, and this desk never recommends positions or picks.