US Senate control after 2026 — Odds & Model Forecast
What the prediction markets imply for US Senate control after 2026, next to the Scopes Poll Composite: the median of independent forecast models.
As of Sep 30, 2026Delayed · publicLive prices, full history & gap alerts → Dashboard
Reading the table: “not listed” means that venue carries no contract for this race; “—” means a contract exists but has no price yet.
| Outcome | Kalshi | Polymarket | Scopes Fair Value | Scopes Divergence |
|---|---|---|---|---|
| Republicans keep the Senate | 37.5% | 37.5% | 48.8% | 11.3 pts |
Model breakdown (1)
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| Democrats take the Senate | 62.5% | 62.5% | 50.5% | 12.0 pts |
Model breakdown (1)
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How the market has moved
The prediction-market price (Kalshi, Polymarket) against the Scopes Poll Composite over time, for Democrats take the Senate. Sampled coarser early, finer as the race nears.
Interactive for subscribers: hover any date for its exact market and Scopes Fair Value reading, and drag to zoom the window. See plans →
How the Scopes Fair Value is set
When a single weight-eligible forecast model publishes a probability for an outcome, its forecast is the Scopes Fair Value. With two or more, the Scopes Poll Composite is their median (median, not mean: one outlier model can't swing it). The models:
- Election Statsheet · Election Statsheet
Earlier series collected from additional sources are retained in the archive and excluded from the composite.
- Scopes Fair Value :
- an independent probability estimate computed from the Scopes Poll Composite: the median of independent election-forecast models.
- Scopes Divergence :
- the difference between the market price and the Scopes Fair Value.
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