KS · Senate 2026 · Updated Oct 28, 2026, 2:01 a.m. ET
Kansas
Rated Lean R
Roger Marshall wins this seat in 64 in 100 simulations. Call it could easily go either way.
Roger MarshallRIncumbent64 in 100- Adam HamiltonD36 in 100
Over time
How the forecast has moved
The margin
How close it lands
Each simulation produces a final margin. The curve shows where those margins fall; the tinted areas on either side of even are the futures each party wins.
Under the hood
What's driving the number
The forecast blends a weighted poll average with a fundamentals model: the state's partisan lean, incumbency, the national environment, and fundraising. Positive points favor the Democratic side of the margin; negative favor the Republican side.
- Partisan leanR +15.8
- IncumbencyR +2.5
- National environmentD +4.7
- FundraisingD +0.6
- Fundamentals sayR +13.0
- The polls sayD +0.4
- Blended forecast marginR +2.5
The blend puts 78 percent of its weight on the polls and 22 percent on the fundamentals; polls take over as more arrive and election day nears.
The field
How other forecasters see this race
Ours isn't the only model on this race. Where another forecaster publishes a number — or we've copied one in by hand from a paywalled model — it appears here beside ours, dated, because models update on their own schedules. Forecasts disagree for knowable reasons: different poll filters, different weights on the fundamentals, different priors.
- Roger Marshall winsThis forecast64 in 100
- Roger Marshall winsRametta & Hare · as of Oct 2757 in 100
No model is "right" before the votes are counted. How our number is made — and how it scored against 2012–2024 races — is on the methodology page.
The markets
What the betting markets say
Prediction markets put a price on this seat too: what people are paying for a contract that pays out if Roger Marshall wins, read as an implied probability. Shown for comparison only. This is not betting advice, and market prices never feed the model.
- Roger Marshall winsThis forecast64 in 100
- Roger Marshall winsKalshi61 in 100
- Roger Marshall winsPolymarket61 in 100
Market prices as of Oct 28, 2026, 2:00 a.m. ET
The evidence
The polls, as the model sees them
Every public poll of this race, with the weight the model gave it in the latest run. Weights reward recency, sample size, and pollster track record; the house adjustment corrects each pollster's habitual lean before averaging.
| Poll | Dates | Sample | D–R | Margin | House adj. | Weight |
|---|---|---|---|---|---|---|
| RedBox Research (D) | Oct 20–23 | 1,301 LV | 45–46 | R +1.0 | −0.1 | 30% |
| InsiderAdvantage (R) | Oct 13–14 | 1,200 LV | 47–48 | R +1.0 | −0.4 | 22% |
| InsiderAdvantage (R) | Oct 9–10 | 1,200 LV | 48–47 | D +1.0 | −0.4 | 8% |
| GBAO (D) | Sep 30–Oct 4 | 600 LV | 49–44 | D +5.0 | −0.3 | 4% |
| YouGov | Sep 24–Oct 4 | 2,255 LV | 48–45 | D +3.0 | +1.5 | 16% |
| Trafalgar Group (R) | Sep 29–Oct 1 | 1,095 LV | 44–44 | Even | −1.7 | 3% |
| New York Times / Siena University | Sep 22–30 | 605 LV | 46–47 | R +1.0 | — | 4% |
| Wedgewood Polls | Sep 22–24 | 500 LV | 50–48 | D +2.0 | +0.1 | 3% |
| Global Strategy Group (D) | Sep 13–16 | 800 LV | 47–43 | D +4.0 | +0.1 | 2% |
| TheHill / Emerson College | Sep 15–16 | 750 LV | 45–43 | D +2.0 | — | 2% |
| Emerson College | Sep 15–16 | 750 LV | 45–43 | D +2.0 | +0.9 | 3% |
| The Hill / Emerson College | Sep 15–16 | 750 LV | 45–43 | D +2.0 | — | 2% |
| co/efficient (R) | Sep 8–10 | 915 LV | 44–49 | R +5.0 | −1.0 | 1% |
| Global Strategy Group (D) | Aug 12–16 | 800 LV | 44–43 | D +1.0 | +0.1 | <1% |
| Public Policy Polling (D) | Aug 7–8 | 569 LV | 45–46 | R +1.0 | +0.2 | <1% |
| GBAO (D) | Jul 8–13 | 600 LV | 43–47 | R +4.0 | −0.3 | <1% |
| Tavern Research (D) | Jan 26–28 | 1,013 LV | 46–54 | R +8.0 | — | 0% |
How the weights, the blend, and the simulation work is spelled out on the methodology page.