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FORECAST51 DAYS OUT
← House3 November 2026 · 51 days out

WA-03 · U.S. House

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The Democratic candidate is narrowly favored to hold WA-03’s House seat. Predicted margin: D+3.0.

A Democrat (D)70 in 10070.2%51.5high 55.2 · low 47.8
A Republican (R)30 in 10029.8%48.5high 52.2 · low 44.8

high / low: vote share (%) in the middle 80 in 100 simulations

About this field

SW Washington; a D holding a Trump seat.

Forecast share averages the simulated vote. Win chance counts how often a candidate wins. A wider range of outcomes can give a candidate a higher win chance despite a lower average share.

Lean D80% range · margin points R+4.3 to D+10.3Democratic-held seat

Forecast history

Steady+0.1 pts · Sep 11 → Sep 13
EVENAug 1Nov 3 · Election Day

Latest reading · Sep 13 · first published Sep 9 · 80% range · margin points R+4.3 to D+10.3. Methodology

Hover the line, tap it, or use the arrow keys to inspect its history.

About this series

This comparable series begins on September 9, 2026, when the model version changed to CTMM 2.2. Earlier readings remain in the archive and are not joined as voter movement; faded points before September 9, 2026 are reconstructions, not forecasts issued on those days.

Faded: CTMM 2.2 reconstructed history: computed after the fact with each date's available polls and environment, without expert ratings; not an issued forecast. Issued forecasts begin at the launch marker.

The polls

Ledger weighted average R+2.1Used by the forecast: 2 polls (60-day half-life) · measured R+3.8 · after the fitted poll-error shift R+3.83 recorded polls · 3 eligible for the aggregate · 2 with positive weight

FieldworkAddedPollsterResultSample
from 2026-07-08Emerson College ↗Northwest Progressive InstituteR+1.0D 42% · R 43%500 LV
from 2026-04-25co/efficient ↗NRCCR+7.0D 34% · R 41%982 LV
Voter Sciences (R) ↗R+7.0D 41% · R 48%600 RV
Explore all 3 polls for this race

How the margin was built

Follow each contribution to the margin. Wider ribbons mean more percentage points. Tap an input for its calculation and source.

Toward D+14.8
Toward R−11.8
Forecast marginD+3.0

The signed totals combine at the forecast. Displayed values are rounded.

All calculations & sources

This district's measured terrain −3.112 points

Call the Map's partisan lean on the CURRENT district lines, before any current-cycle evidence. Every pull below is measured from here — not from EVEN.

  • Call the Map partisan lean, district geography bound to this forecast edition.
  • Prior source: observed_unchanged_lines.

Fitted model, above the terrain shown +13.427 points

What the fitted model adds on top of the starting terrain above — incumbency, past results, campaign finance and the other fitted terms — measured from that terrain rather than from EVEN. It is a comparison with the starting point already shown, not a separate input. The source detail lists the variables the fit uses.

  • Fitted baseline 10.315 minus starting point -3.112 = 13.427 points.
  • Presidential-margin-by-congressional-district dynamic core.
  • Presidential-margin-by-congressional-district dynamic core (Jul 8 2026 deploy): a mass fit across district demographics, fundraising, incumbency, and past-cycle overperformance, trained on all 435 districts at once instead of a hand-built lean+incumbency recipe.
  • The work: the core's fitted terms sum to +10.3 — the fundamentals row.
  • fundamentals core = 25-term dynamic formula (mass fit over the master feature matrix, held-out-cycle validated; see matrix/feature_dictionary.md + mass_fit_report.json)
  • 40-term formula, held-out validated.

National environment +1.365 points

The contribution to this race’s margin, not the national polling margin itself. The race’s loading, reference level and polling blend determine how much of the national climate reaches its final forecast.

  • Three-source blend, updated 2026-09-08: 52% generic-ballot aggregates (D+6.5) · 28% special-election overperformance (D+9.0 across 46 specials) · 20% approval-implied (D+8.6 from net approval -21.7).
  • Latest polls — generic ballot 2026-09-08 (5 days old), approval 2026-09-10 (3 days old).
  • Generic-ballot average D+6.5 · support factor 0.84 (the share of that channel's capacity the admitted polls carry) — separate inputs; their product is a capacity diagnostic, not a margin.
  • Weights are the 55/25/20 capacities scaled by each channel's evidence and renormalized, so thin polling widens the interval instead of pulling the center toward zero — 16% of the weight is carried that way.
  • Blended national environment: D+7.6.
  • Applied at full strength to this chamber's races.
  • The work: national environment × 1 chamber strength = +1.4 of this margin.
  • Blended national environment: D+7.6 (updated 2026-09-08).
  • Effective poll weight 84%; fundamentals share 16%, carried by the interval (×1.08) rather than by the center.
  • The support factor is the share of the generic-ballot capacity the admitted polls carry; average × support is a capacity diagnostic, not a margin, and is not what the row above multiplies.
  • Applied at full strength to this chamber: +1.4 of this margin.

This race’s polls −8.666 points

What this race’s own recent polling adds beyond its prior, after each poll is weighted for recency, sample size and pollster quality.

  • Emerson College (2026-07-10, n=500): R+1.0 · weight 0.11
  • co/efficient (2026-04-29, n=982): R+7.0 · weight 0.01
  • Voter Sciences (R) (2025-08-20, n=600): R+7.0 · weight 0.00
  • Adjusted poll-bank aggregate R+2.1 · 3 recorded polls · 3 eligible for the aggregate · 2 with positive weight. The sealed model records a net polling contribution of −8.7 D. Observation weights are not the final model blend weight. Eligible polls: latest poll: 2026-07-10 (65 days old).
  • Adjusted poll-bank aggregate R+2.1 · 3 recorded polls · 3 eligible for the aggregate · 2 with positive weight; recorded polling contribution −8.7 D. These observation weights must not be read as the model’s final prior-versus-polling weight. Eligible polls: latest poll: 2026-07-10 (65 days old).

The components this edition publishes for this race, in points. “Other factors” closes the sum to the two-party structural lean exactly. Here the structural lean IS the published margin, so the walk sums to the projection exactly; nothing is left over.

Named factorContribution
FundamentalsThe admitted fitted baseline. Its surviving variables differ by office; the source detail above identifies those used for this race.+10.31
This race's pollsAdmitted head-to-head polls of this race, recency- and quality-weighted.−8.67
National environmentThe national environment’s contribution to the prior. Polling can attenuate its influence; this value is not the national polling margin.+1.37
Other factors0.00

Recent elections

ElectionResultVotes cast
2024 · U.S. House ↗D+3.9415,904
2022 · U.S. House ↗D+0.8319,759
2020 · U.S. House ↗R+13.0417,903
2018 · U.S. House ↗R+5.3307,226

Historical district boundaries may differ. Margins compare Democratic and Republican vote totals. Nonstandard ballots are labeled separately.

Race context

Forecast votes cast
318,288
2024 presidential margin
R+3.4

Population profile Select a measure for its source and denominator

White alone · 81.5%627,373 of 770,201 · Residents2022 Census · matched race geography
Demographic source and limits

U.S. Census Bureau, 2022 American Community Survey 5-year estimates ↗

Coverage

1 story · 1 quote

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