2026 Senate forecastThe Upper Chamber by Son Ha

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IL · Senate 2026 · Updated Oct 28, 2026, 2:01 a.m. ET

Illinois

Rated Solid D

Juliana Stratton wins this seat in 97 in 100 simulations. Call it all but certain.

  • Portrait of Juliana StrattonJuliana StrattonD97 in 100
  • Don TracyR3 in 100

Over time

How the forecast has moved

0255075100AprJulOctJan ’26AprJulOctD 97 in 100R 3 in 100Oct 28, 2026
Chance in 100 the seat goes to each side: blue for the Democratic caucus, red for the Republicans · one point per day · hover or tap to read the lines

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.

EvenD +16.8
← Don Tracy aheadJuliana Stratton ahead →
Where the simulated margins land · marker at the average margin

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 leanD +12.4
  • IncumbencyEven
  • National environmentD +4.7
  • FundraisingD +0.3
  • Fundamentals sayD +17.3
  • The polls sayD +15.9
  • Blended forecast marginD +16.9

The blend puts 28 percent of its weight on the polls and 72 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.

  • Juliana Stratton winsThis forecast97 in 100
  • Juliana Stratton winsRametta & Hare · as of Oct 27>99 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 Juliana Stratton wins, read as an implied probability. Shown for comparison only. This is not betting advice, and market prices never feed the model.

  • Juliana Stratton winsThis forecast97 in 100
  • Juliana Stratton winsKalshi98 in 100
  • Juliana Stratton winsPolymarket98 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.

PollDatesSampleD–RMarginHouse adj.Weight
ActiVoteSep 26–Oct 20400 LV58.5–41.5D +17.0+0.160%
Public Policy Polling (D)Sep 30–Oct 1569 LV49–36D +13.0+0.240%

How the weights, the blend, and the simulation work is spelled out on the methodology page.