Illinois · Governor

Who is running?

JB Pritzker (Democratic), Darren Bailey (Republican), Collin Corbett (Independent). The margin below is JB Pritzker minus the other candidate in the main contest; the rest are on the ballot and not in it.

The race, in brief

Illinois elects its governor on November 3, 2026. The text describes a moderately to strongly blue state, carried by Democrats by double-digit margins in every presidential race since 1992, with Republicans favored in much of rural West Central and Southern Illinois. The state profile on file gives a non-Hispanic white share of 0.6, a Hispanic share of 0.185 and a Black share of 0.1.

Democratic incumbent JB Pritzker, governor since 2019, is seeking a third term, having won by 15.6% in 2018 and 12.5% in 2022; Illinois has no gubernatorial term limits. His running mate is former deputy governor Christian Mitchell, as Lieutenant Governor Juliana Stratton is running for the Senate. He was unopposed in the March 17 primary. The Republican nominee is Darren Bailey, a former state senator and the 2022 nominee, making this the first gubernatorial rematch in the state since 1986; the lead gives him 54% of the primary vote, while the results table's top line reads 53.3% with candidate names missing. His running mate is Aaron Del Mar, chair of the Cook County Republican Party.

All seven raters listed call the race D, among them the Cook Political Report (August 20, 2026) and Sabato's Crystal Ball (August 12, 2026). The one general-election poll, Victory Research (November 20–24, 2025), had Pritzker 54%, Bailey 34%.

A paragraph quoting a model forecast from the day this brief was written is omitted; the current forecast is at the top of this page.

The facts, each beside its sentence

Not in the source: No fundraising figures in the text.; Republican primary results table has lost the candidate names; only the lead's 54% attributes a share to Bailey.; The only general-election poll dates from November 2025.; The facts list JB Pritzker with incumbent: false, while the text calls him the incumbent.; The facts give no forecast basis.

Read from the district's section of Wikipedia's state page (CC BY-SA), archived as 2afffa5f81bf; written by claude-fable-5-1 (batch reader) on 2026-09-30 and checked mechanically: every quote occurs verbatim in the archived text, every number in the brief occurs in the inputs. No probability here is the reader's.

How it has voted for president

A shift of 6.9 points toward the Republicans from 2016 to 2024. county returns summed; MEDSL county file (2016), an MIT-licensed county file (2020, checked against certified state results) and MEDSL precinct returns (2024). For a district split across counties this is an estimate, and where the state published the exact 2024 figure for these lines, that exact figure is the one the model uses.

The state in numbers

ACS 5-year state tables; BLS county unemployment and BEA county income, transfers and jobs summed to the state. Every figure is a named column of a named public-domain table, archived before it was read.

Who is ahead, and by how much?

Two numbers because they answer two questions. The nowcast is where opinion stands; the election-day forecast is where it is likely to end up.

How likely is each to win?

Monte Carlo error is ±0.1 points. A change smaller than that is simulation noise rather than news, and this page will not describe it as movement.

How wide is the range?

Nowcast: 90% of simulations fall between +0.7 and +36.0 points. Election day: +0.5 to +38.3. The election-day interval is 2.4 points wider, which is the 33 days of movement still to come.

What is the uncertainty made of?

Total sd 11.53 points, made of latent opinion 65%, race-specific polling error 19%, drift to election day 12%, correlated polling error 4%. The decomposition is stored with the forecast rather than reconstructed, so a probability whose dominant input is a placeholder is visibly that.

What evidence is this built on?

1 polls, most recent 2025-11-24. every input is provisional.

What changed since the last run?

Shaded band is the 90% interval, line is the central estimate, positive is JB Pritzker ahead of Collin Corbett. Over 13 stored forecasts the central estimate moved -0.5 points. There were 6 specification changes (marked on the axis) and no new polls arrived over this window — so every movement in this chart is a change to the model, not a change in the race.

Since 2026-10-01: margin +0.00 points, win probability +0.0 points, on +0 polls.

Not answered here: why it changed. Splitting a move into new polls, time and specification means re-running the earlier model against the later inputs -- two extra posterior fits -- so it is computed on a cadence (scripts/attribute_forecasts.py) rather than while you wait. This pair of runs has not been decomposed yet. The size of the move is shown; the cause is not guessed at.

How has this model done before?

Measured on 230 forecasts across 230 races in cycles 2016,2018,2020,2022,2024: mean absolute error 4.56 points, Brier score 0.0543. The nominal 90% interval contained the result 94% of the time, the 80% interval 84%, and the 50% interval 47%. Read that with care: a national polling miss moves every race in a cycle at once, so the sample size for a question about the intervals is 5 cycle(s), not 230 forecasts. Per cycle -- bias +1.644 pts; 2016: n=43 bias=+4.68 cov90=0.860; 2018: n=63 bias=-0.52 cov90=1.000; 2020: n=35 bias=+5.44 cov90=0.886; 2022: n=54 bias=-0.60 cov90=0.944; 2024: n=35 bias=+1.48 cov90=1.000.

Where did every number come from?

Nowcast run 288a6260-a419-4aa9-9c56-59dad5627f2c and election-day run 4e087175-3a0a-4d8b-b8c5-ccbe7f353a7f, model single_race_latent/0.8.1 at commit bdf7e83107c17a2399efe61a44ef1bbee48f9284, seeds 20260924 and 20260924.