Pennsylvania · Governor

Who is running?

Josh Shapiro (Democratic), Stacy Garrity (Republican), Ken Krawchuk (Libertarian). The margin below is Josh Shapiro minus the other candidate in the main contest; the rest are on the ballot and not in it.

The race, in brief

Pennsylvania elects its governor on November 3, 2026. The text calls it a purple state, narrowly won by Donald Trump in 2024 and 2016 and by Joe Biden in 2020; Republicans have not won a gubernatorial election there since 2010. The state profile records a median household income of 76081.0, a white non-Hispanic share of 0.7 and a college share of 0.3.

Democratic governor Josh Shapiro, first elected with 56.5% in 2022, seeks a second term with lieutenant governor Austin Davis. The Republican nominee is state treasurer Stacy Garrity, with Jason Richey as running mate. Both nominees were unopposed in the May 19 primaries (Shapiro 1,116,960 votes, Garrity 641,534). Libertarian Ken Krawchuk is also running; the Green candidates were removed from the ballot. AI data centers have become a campaign issue.

Every rater listed calls the race D: the Cook Political Report, Decision Desk HQ, Fox News, Inside Elections, RealClearPolitics, Sabato's Crystal Ball and Silver Bulletin. The text's polling average is Shapiro 55.6%, Garrity 32.7%, or Shapiro +22.9%. The most recent listed poll, New York Times/Philadelphia Inquirer/Siena (September 15–22, 2026), has Shapiro 58%, Garrity 38%; the closest, National Public Affairs, a Republican firm (July 26–30), has Shapiro 50%, Garrity 43%.

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: facts.candidates marks Shapiro as incumbent: false, but the text says he is the Democratic incumbent seeking a second term.; facts.forecast carries no basis field, so it is not stated whether the model used the statewide polls the text lists.; The text gives no fundraising figures for either campaign.; The text gives no ratings finer than 'D' (no Lean/Likely/Safe).; The general-election results table is empty (race not yet held); no endorsement lists are populated beyond the declined candidates' notes.

Read from the district's section of Wikipedia's state page (CC BY-SA), archived as d80fa0d89a98; 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 1.0 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 ±0.0 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 +9.9 and +28.8 points. Election day: +6.9 to +29.5. The election-day interval is 3.7 points wider, which is the 33 days of movement still to come.

What is the uncertainty made of?

Total sd 7.21 points, made of race-specific polling error 48%, drift to election day 31%, correlated polling error 11%, latent opinion 10%. 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?

15 polls, most recent 2026-09-22. 47% verified against a primary source.

What changed since the last run?

Shaded band is the 90% interval, line is the central estimate, positive is Josh Shapiro ahead of Ken Krawchuk. Over 15 stored forecasts the central estimate moved -1.4 points. There were 7 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 7ddcfba5-8e6f-4321-8a53-83a8d9ab5167 and election-day run 9f452cc6-dacf-4e06-af06-484384773654, model single_race_latent/0.8.1 at commit bdf7e83107c17a2399efe61a44ef1bbee48f9284, seeds 20260924 and 20260924.