AgentFlarePrediction Markets · Wed, Oct 28, 2026
Traders price a Democrats sweep of the 2026 midterms at 65.5%, well ahead of rivals
Polymarket's Balance of Power event puts Democrats Sweep at 65.5% implied probability, with the market ending 2026-11-04. Odds are market-implied, not forecasts.
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What the market asks and how it resolves
The event asks which party wins control of the United States Senate and which wins control of the House in the 2026 midterm election. Control requires a majority of voting seats. If no party holds a majority, a Senate tie-break uses the Vice Presidency, and a House deadlock falls to the party of the first elected Speaker of the next Congress. Resolution therefore depends on seat counts and on these fallback rules, not on national vote totals.
How traders price it now and how that moved
Democrats Sweep is priced at 65.5%, up from a starting level of 60.5% over the last 56 half-day points. The series peaked at 68.5% and bottomed at 60.5%, a rise of 5.0 percentage points. The event has total volume of $40.05M and $1.30M over 24 hours across 5 active markets. Movement in the sweep contract reflects shifting trader expectations about seat outcomes as the November 4 end date approaches.
How concentrated the odds are
Pricing is concentrated in two outcomes. Democrats Sweep sits at 65.5%, and R Senate, D House follows at 26.5%. Republicans Sweep is at 7.5%, while D Senate, R House is at 1.0% and Other at 0.1%. The split shows traders see a Democratic trifecta as most likely, with a divided government with Republicans holding the Senate as the main alternative.
Current odds
| Market | Yes | Volume |
|---|---|---|
| Democrats Sweep | 65.5% | $8.62M |
| R Senate, D House | 26.5% | $5.45M |
| Republicans Sweep | 7.5% | $12.48M |
| D Senate, R House | 1.0% | $8.46M |
| Other | 0.1% | $5.04M |
What decides this market
- Control of the Senate requires a majority of voting seats, with the Vice Presidency breaking an even split.
- Control of the House requires a majority of voting seats, with the first elected Speaker deciding deadlocks.
- Ambiguous outcomes fall to the party of the first selected President Pro Tempore of the next Congress.
Resolution rules
This market will resolve according to the party that wins control of the United States Senate and the party that wins control of the United States House of Representatives in the 2026 United States midterm election. A party wins control of the United States Senate if it wins a majority of the chamber’s voting seats. If no party wins a majority of voting seats, the party that wins control of the chamber is the party that wins half of the voting seats and holds the Vice Presidency. If the outcome remains ambiguous after applying the above criteria, the chamber will be deemed controlled by the party with which the first selected President Pro Tempore of the Congress that convenes after the spec…
Quoted from the market's description on Polymarket.
FAQ
What does the Democrats Sweep price mean?
It is the market-implied probability that Democrats win control of both the Senate and the House in the 2026 midterm election. At 65.5%, traders are pricing that outcome as the most likely of the listed options.
How does the Vice Presidency affect Senate control?
If no party wins a majority of voting seats, the party that wins half of the seats and holds the Vice Presidency controls the chamber. This tie-break applies before the President Pro Tempore fallback.
Why does the market end on 2026-11-04?
The event lists 2026-11-04 as its end date, which is when trading closes. Resolution then follows the seat-count and fallback rules in the resolution text.
How this page is made. Odds, volume and price history come from the AISA Polymarket APIs (Gamma events and CLOB prices-history). The analysis is written by a language model from those numbers and the market’s own resolution text only — any figure not in that data is removed. Probabilities are what traders are paying, not forecasts.