AZ-5 · House

The district, in brief

Arizona's 5th is based in the East Valley, including Gilbert and portions of Chandler and Mesa, on the map first used in 2022; it is not redrawn for this cycle. The text gives no presidential result for the district.

The seat is open: the incumbent, Republican Andy Biggs, reelected with 60.4% in 2024, is retiring to run for governor. The Republican nominee is Mark Lamb, former Pinal County Sheriff (2017–2024) and a 2024 candidate for U.S. Senate, who beat construction contractor Daniel Keenan in the primary; the results table in the text is garbled and gives no vote figures. Jay Feely withdrew on December 19, 2025 to run in the 1st district, and former state representative Travis Grantham withdrew on March 12, 2026. The Democratic nominee is Elizabeth Lee, who won her primary with 66.0% (30,857 votes) over Chris James at 20.8% and Brian Hualde at 13.2%; the text gives no background for her. As of July 1, 2026 Lamb had raised $1,222,217 with $243,426 on hand; Lee had raised $153,111 with $26,740 on hand. Keenan raised $1,851,302, of which $1,650,620 was self funded.

Five raters call the seat R: Decision Desk HQ (July 14, 2026), the Cook Political Report and Inside Elections (June 30, 2025), Sabato's Crystal Ball (July 10, 2025) and The Economist (May 6, 2026); Silver Bulletin is listed with a date of August 20, 2026 but no ranking shown. The only polls in the text are of the Republican primary; none tests the general election.

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: The text gives no presidential results for the district, and the facts carry no presidential baseline.; The Republican primary results table is garbled: no vote counts or percentages for Lamb versus Keenan.; The Democratic primary section header and candidate descriptions are missing; Elizabeth Lee's background is not given.; No general-election polls; all polls listed are of the Republican primary. The model's basis says no district polls.; Silver Bulletin's rating is missing from the predictions table (date shown, no ranking).; Ratings are given only as 'R' with no Lean/Likely/Safe gradation.; No post-primary endorsements are listed.

Read from the district's section of Wikipedia's state page (CC BY-SA), archived as 389ca3f89b96; 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.

Who holds the seat now

Andy Biggs (Republican), in this chamber since 2017, 5 terms. Committees: House Committee on the Judiciary; House Committee on Oversight and Government Reform.

From the congress-legislators dataset (CC0), archived as ae8cb9477c48. For a Senate race this lists both of the state's senators; the one whose term ends in the election year holds the seat on the ballot. For a House district redrawn for 2026 it is the member elected under the old lines with this number, who may be running elsewhere; the dossier above names who is running here.

How it has voted for president

A shift of 1.3 points toward the Republicans from 2016 to 2024. county returns placed on the current lines by 2020 block population; 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.

Who are the voters?

Of about 522,277 adults 25 and over. In 2020 the district voted 41.7% Democratic (two-party) for president. With the same preferences and a 2022-style midterm turnout, it would vote 41.6% Democratic: the midterm electorate alone moves the margin 0.2 points toward Republicans. Group shares are estimated from how results vary across the state's census tracts (ecological inference, anchored to Pew's 2020 validated-voter figures) and calibrated to this district's actual 2020 vote; turnout is the Census survey's state rate by race and national rate by education, whose state samples carry margins of several points.

Not answered here: how each group will vote in 2026. These are 2020 preferences; this profile is description, not yet an input to the forecast.

The money

FEC bulk candidate summaries through July 08, 2026; $348,184 of independent expenditures for or against these candidates this cycle (FEC Schedule E, types 24E and 24A), which is the parties' and outside groups' own revealed view of whether this seat is in play.

The district in numbers

ACS 5-year 2023, the Census Bureau's own tabulation of this district (118th Congress lines). Unemployment is the BLS county series placed on the district by block population, not seasonally adjusted, so changes are same-month comparisons. Income, transfers and jobs are BEA county accounts placed the same way, compared with the average district. Every other figure is a named column of a named table in the Bureau's summary file, archived before it was read. This is what a reader knows about a district before looking at a poll; the model does not yet use it, and whether it should is a registered question.

Who is favoured, and by how much?

The 90% interval runs from -23.5 to +6.3 points, D-R. It is wide because this district has never been polled.

What is this built on?

A model trained on every contested House race 2012-2024 predicts this district's lean from its own record: presidential and House results on the current lines, incumbency, both candidates' prior offices, outside and party money before 1 October, demographics and public-assistance shares from the Census release before the election, local unemployment and income, and religious tradition. The national margin comes from presidential approval, the economy, the midterm penalty and the generic ballot corrected for its measured lean. Draws share national and state errors, so the seat total and this district come from the same simulation.

Not answered here: district polls, which are not yet folded in.

Why does the model say this?

Each figure is how far this district's predicted lean moves when that one feature is set to the typical value across 2026 districts, everything else held: 2024 presidential lean (R+18.9): 7.4 pts toward the Republican; 2024 House lean (R+18.1): 2.6 pts toward the Republican; outside money balance: 0.6 pts toward the Democrat; median hh income ($109,782): 0.6 pts toward the Republican; asian share (5.8%): 0.4 pts toward the Democrat.

How sure is it, and of what?

Total sd 9.11 points, made of the seat's own volatility 90%, correlated polling error 10%. The decomposition is stored with the forecast rather than reconstructed, so a probability whose dominant input is a placeholder is visibly that.

Not answered here: a nowcast. 'If ballots were cast today' needs something that observes today, and for a House district nothing does. Publishing the election-day figure under both labels would make one forecast look like two.

How was this number made?

Run 6f211e6f-2bdc-4dda-8f72-81fc628dab0b, house_district_prior/0.2.0, as of 2026-10-02. Promoted by a pre-registered gate: on 2016-2022 its Brier score was 0.036 against 0.049 for the previous method, and on a single 2024 run 0.023 against 0.032 (experiments/district_gate_result.md, with an independent review).