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Will Republican win the House race for WA-04? — Republican party

KXHOUSERACE-WA04-26-R · Elections · 2026-04-25
91%
Agent
84%
Market Price
+7.0%
Edge
78%
Confidence
Volume: 19,003
Spread: 1.0c
Days to resolution: 556
Markets in event: 2
Final Rationale
WA-04 is an R+10 open seat with multiple credible Republican candidates (including state senator Boehnke) and no Cook competitive rating, which structurally anchors the forecast in the low-90s based on historical flip rates for R+10 open seats. I partially accept the Devil's Advocate critiques: the base rate may be modestly overstated (92-95% rather than 95-98%), open-seat dynamics with ~190 days to election create real residual uncertainty, and jungle primary vote-splitting is a small tail risk — adjusting from 93% to 91%. I reject moving all the way to the 84% market price because the market reliability is unknown (no volume/orderbook data) and the structural fundamentals strongly support a higher number; even in 2018's D+8.6 wave, R+10 open seats essentially didn't flip. The 7-point deviation from market is justified by the unverified market signal combined with strong, specific structural evidence (PVI, candidate field, forecaster ratings).
Price vs. prediction
How the market moved after the agent's call. Solid blue line is the actual market price; dashed line is the agent's static forecast at $t{=}0$.
$n = 58$ follow-ups
1. Planner Opus · Fermi decomposition + tool plan
Tools chosen: kalshi_data kalshi_orderbook article_search web_search wikipedia_lookup
Sub-questions (Fermi decomposition)
  1. Is WA-04 currently held by a Republican, and does the incumbent plan to run for re-election in 2026? (w=0.25)
  2. Does WA-04 have a strong Republican lean based on historical voting patterns and Cook/Sabato ratings (e.g., R+10 or greater)? (w=0.35)
  3. Will the 2026 national political environment (wave elections, redistricting, candidate quality) favor Republicans winning WA-04? (w=0.25)
  4. Have prediction markets or forecasters rated WA-04 as likely or safe Republican for the 2026 cycle? (w=0.15)
Planner reasoning
WA-04 covers central Washington (Yakima Valley, Tri-Cities region), historically a strongly Republican district. The key questions are: (1) incumbency advantage — Dan Newhouse has held this seat since 2015 and was one of 10 House Republicans who voted to impeach Trump; he narrowly survived a 2022 primary challenge but won re-election. Whether he runs again in 2026, faces a Trump-aligned primary challenger, or retires matters significantly. (2) Partisan lean — WA-04 is a deep-red district (Trump won it by ~20+ points in 2024), making a Democratic general election flip extremely unlikely absent extraordinary circumstances. (3) The main risk scenario is a Republican primary producing a weak nominee, but even then the district's deep red lean would likely sustain a Republican win in the general. Reference class: districts with R+15 or greater partisan lean almost never flip in general elections. Temporal analysis: With 556 days until resolution, the key sequence is: primary filing (spring 2026) → primary election (August 2026) → general election (November 2026) → swearing in (January 2027). The main uncertainty is the primary, but the general outcome is near-certain Republican given the district's partisan makeup. The forecast should be very high probability Republican (85-95%+), with the main downside being an extraordinary national environment shift or unusual candidate quality issues.
2. Research Parallel tool calls · legacy v2
ToolStatusTimeItemsSummary
kalshi_data OK 1.9s -
kalshi_orderbook OK 0.1s -
article_search OK 0.7s -
web_search OK 36.3s -
wikipedia_lookup OK 1.0s -
3. Evidence Synthesis Sonnet · 12 items · legacy v2
#StrengthCredibilityDirectionSourceClaimPriced In
1 STRONG 82 NEUTRAL web_search Dan Newhouse (R) currently holds WA-04 but has announced he will NOT seek reelection in 2026, making it an open-seat contest. Yes
2 STRONG 90 ↑ UP wikipedia_lookup Dan Newhouse has represented WA-04 since January 3, 2015, as a Republican; the seat has been continuously Republican-held. Yes
3 MODERATE 75 ↑ UP web_search State Sen. Matt Boehnke (R-Kennewick) is a notable Republican candidate entering the WA-04 race to replace Newhouse; other Republican candidates include John Duresky, Amanda McKinney, Wesley Meier, and Jerrod Sessler. Yes
4 STRONG 88 ↑ UP web_search WA-04 has a Cook PVI of R+10, making it the most Republican congressional district in Washington state and the 129th most Republican district nationally. Yes
5 STRONG 90 ↑ UP wikipedia_lookup WA-04 covers central Washington (Yakima Valley, Tri-Cities) and is rated R+10 by Cook PVI, the most Republican district in Washington. Yes
6 STRONG 82 ↑ UP web_search WA-04 does not appear on Cook Political Report's publicly available competitive race lists (Toss-Up, Lean, or Likely Democratic/Republican) as of March 12, 2026, strongly implying a Solid/Safe Republican rating. Yes
7 MODERATE 65 ↓ DOWN article_search The 2026 national environment shows some Democratic momentum due to an unpopular war with Iran and affordability issues, with more voters preferring Democratic control of Congress in CBS polling as of March 2026. Yes
8 MODERATE 72 ↑ UP article_search Even with a potentially favorable Democratic national environment in 2026, WA-04's R+10 PVI makes a Democratic flip extremely unlikely; districts of this partisan strength rarely flip even in wave elections. Yes
9 WEAK 60 NEUTRAL article_search California's Prop 50 redistricting (passed Nov 2025) affects California seats but has no bearing on WA-04 boundaries; no redistricting affecting WA-04 has been reported. Yes
10 MODERATE 70 ↑ UP article_search Multiple Republican primary candidates are running in WA-04, including a credible state senator (Boehnke), which suggests candidate quality is unlikely to be catastrophically low for Republicans. Yes
11 STRONG 80 ↑ UP web_search Cook Political Report does not list WA-04 among competitive races as of March 2026, implying it is effectively rated Solid/Safe Republican by the major forecasting outlet. Yes
12 WEAK 50 ↑ UP web_search No Sabato's Crystal Ball or Inside Elections ratings were found for WA-04 in the research data; the absence from competitive race lists across forecasters is consistent with a safe Republican designation. Yes
Information Gaps
  • No direct Sabato's Crystal Ball or Inside Elections rating for WA-04 2026 was found — only Cook Political Report inference from absence on competitive lists.
  • No Kalshi or prediction market price data for this specific race was provided.
  • No Democratic candidate has been identified for WA-04 2026; an unusually strong Democratic candidate could marginally affect odds but is currently unknown.
  • The full Cook Political Report narrative rating for WA-04 is behind a paywall — exact rating (Solid vs. Safe R) not confirmed directly.
  • Trump's 2024 margin in WA-04 was referenced as ~20+ points in the reasoning prompt but not confirmed from primary sources in the research data.
  • No polling data specific to WA-04 2026 general or primary race was found.
  • Exact filing deadlines and final candidate list for WA-04 August 4 primary are not confirmed in the research.
Key Uncertainties
  • Whether a weak or scandal-prone Republican emerges from the August 4 top-two primary — though even weak nominees in R+10 districts rarely lose generals.
  • Severity of the 2026 Democratic wave environment: the Iran war and affordability concerns are cited as boosting Democrats, but it is unknown how much this shifts deep-red districts.
  • Whether a strong independent or write-in candidate could siphon enough Republican votes in WA's top-two primary system to prevent two Republicans from advancing (making a D vs. D or D vs. R general possible, though extremely unlikely given partisan lean).
  • Washington's top-two primary system: if two Democrats advance (highly unlikely given R+10 PVI but theoretically possible), the general would automatically produce a Democratic winner.
  • National environment trajectory between now (April 2026) and November 2026 — the Iran war situation and economic conditions could shift significantly.
Market Context
Price: None · 7d: None · 30d: None
Volume: UNKNOWN · Depth: UNKNOWN
Reliability: NO DATA — No Kalshi or prediction market data was present in the research for this specific race
4. Independent Forecaster Opus · No market price · legacy v2 Did NOT see market price
Independent estimate: 93% (82% confidence)
base rate
92%
82% conf
evidence driven
94%
85% conf
contrarian
93%
78% conf
Spread
2pp
Low disagreement
sq1: Is WA-04 currently held by a Republican, and does the incumbent plan to run for re-election in 2026?
15%
Newhouse has announced he will NOT seek reelection. The seat is R-held but the second condition fails. This is essentially a factual question with a clear answer: Republican-held YES, but incumbent running NO. Combined as 'and', this is NO. Estimate ~15% to account for any residual uncertainty about reversal.
sq2: Does WA-04 have a strong Republican lean (R+10 or greater)?
97%
Cook PVI confirmed at R+10. Multiple sources confirm. This is a factual yes.
sq3: Will the 2026 national environment favor Republicans winning WA-04?
88%
Base rate: R+10 districts essentially never flip — in 2018 wave (D+8.6 national env), almost no R+10 districts flipped. Even with Democratic momentum from Iran war/affordability, WA-04's structural lean dominates. Multiple credible R candidates including a state senator suggests no candidate quality collapse. Top-two primary risk of two Dems advancing is near-zero given R+10. Slight downward pressure from open seat + Dem environment, but R win remains highly likely.
sq4: Have forecasters rated WA-04 as likely/safe Republican?
95%
Absence from Cook competitive lists strongly implies Solid R rating. Standard for R+10 open seats.
Show full reasoning trace
base rate: Base rate for R+10 open-seat House districts being won by Republicans in general elections is approximately 95-98% over the past several cycles. Even in wave years (2018: D+8.6 environment), R+10 districts almost never flipped to Democrats. Open seats slightly increase volatility but don't fundamentally change the partisan outcome.
evidence updates: R+10 PVI confirmed (strong UP, anchors at base rate ~95%). Open seat with Newhouse retiring (slight DOWN ~3%, increases uncertainty). Multiple credible Republican candidates including state senator Boehnke (UP ~2%, ensures viable nominee). Democratic-favoring 2026 environment (DOWN ~2%, but limited impact in R+10). Top-two primary in WA creates small tail risk of two Dems advancing (DOWN ~0.5%, near-zero in R+10). Net: ~92%.
combination method: The sub-question structure has sq1 mechanically scoring low because Newhouse isn't running, but this doesn't materially affect R-win probability. Substantively combining the partisan lean, environment, and forecaster ratings yields ~92%.
final: WA-04 is an R+10 open seat with multiple credible Republican candidates and is not flagged as competitive by Cook. Despite a slightly Democratic-leaning national environment and Newhouse's retirement, the structural partisan lean overwhelmingly favors a Republican winning the general election. Final estimate: 92%.
ensemble: {'ensemble_count': 3, 'perspectives': {'base_rate': {'p_yes': 0.92, 'confidence': 0.82}, 'evidence_driven': {'p_yes': 0.94, 'confidence': 0.85}, 'contrarian': {'p_yes': 0.93, 'confidence': 0.78}}, 'spread': 0.02, 'individual_p_yes': {'base_rate': 0.92, 'evidence_driven': 0.94, 'contrarian': 0.93}}
5. Devil's Advocate Sonnet · legacy v2 Market price revealed
Reasoning Flaw
Challenges
  1. The sq1 sub-question is poorly constructed — it conjoins 'R-held' AND 'incumbent running' which mechanically scores low when Newhouse retires, but this doesn't reduce R-win probability. The forecaster correctly notes this in the combination_method, so this is a meta-issue: the decomposition itself was flawed and the model overrode it qualitatively. This is acceptable but worth flagging.
  2. Resolution is 556 days away (Nov 2027 close, but election is Nov 2026 ~190 days out). Significant uncertainty remains: no Democratic candidate identified, primary not yet held, possible scandal/candidate-quality shocks. The 93% may be slightly overconfident given how much can happen in 6+ months including a contested R primary.
  3. Top-two jungle primary in WA creates a non-trivial tail risk that's underweighted: with multiple R candidates splitting the vote, it's possible (though unlikely) that vote-splitting elevates a Democrat to a stronger-than-expected position, or in rare cases two Republicans advance (which would still resolve YES, mitigating this risk). But a fragmented R field with a consolidated D could underperform PVI.
  4. Base rate citation '95-98% for R+10 open seats' is asserted but not rigorously sourced. Actual historical flip rate for R+10 open seats in neutral-to-D environments may be closer to 92-95%, especially with retirement of long-time incumbent who had personal brand.
  5. The forecaster dismisses 2026 D environment as having 'limited impact in R+10' but a true wave (D+8 to D+10 national) historically has flipped a small number of R+10 seats. The evidence cites Iran war + affordability concerns — these aren't priced as carefully as they could be.
Suggested adjustment: -3pp
Minor downward adjustment warranted not because of market divergence, but because: (1) base rate may be slightly overstated, (2) ~190 days until election leaves room for unforeseen shocks (candidate scandals, contested R primary outcomes), (3) jungle primary vote-splitting risk is real though small. 90% is more defensible than 93%. The market at 84% is plausibly pricing some additional risk premium plus uncertainty discount that the forecaster's structural analysis legitimately discounts, so I don't suggest moving all the way to market.
Market comparison: Forecaster: 93%, Market: 84%. The 9-point gap is notable but the market data has NO RELIABILITY (no volume/orderbook). The forecaster's structural case (R+10, no competitive rating, multiple R candidates) is strong and largely justifies being above market. A small adjustment to ~90% accounts for genuine residual uncertainty (open seat, time to election, unknown D candidate) without capitulating to an unverified market price.
6. Aggregator Opus · final calibrated forecast
91% (78% confidence)
WA-04 is an R+10 open seat with multiple credible Republican candidates (including state senator Boehnke) and no Cook competitive rating, which structurally anchors the forecast in the low-90s based on historical flip rates for R+10 open seats. I partially accept the Devil's Advocate critiques: the base rate may be modestly overstated (92-95% rather than 95-98%), open-seat dynamics with ~190 days to election create real residual uncertainty, and jungle primary vote-splitting is a small tail risk — adjusting from 93% to 91%. I reject moving all the way to the 84% market price because the market reliability is unknown (no volume/orderbook data) and the structural fundamentals strongly support a higher number; even in 2018's D+8.6 wave, R+10 open seats essentially didn't flip. The 7-point deviation from market is justified by the unverified market signal combined with strong, specific structural evidence (PVI, candidate field, forecaster ratings).
7. Entry Decision Opus Trader
Side
YES
Position Size
$900
Contracts
1059
Trader Confidence
78%
Trade Rationale
Edge is +7% on a structurally well-supported forecast: WA-04 is R+10, multiple credible Republican candidates, and historical flip rates for R+10 open seats are extremely low even in wave years. Forecaster confidence is solid at 0.78 and the rationale appropriately incorporates Devil's Advocate concerns. However, the edge is modest (just above the 5% threshold), liquidity is UNKNOWN with zero orderbook depth, resolution is 556 days out, and the portfolio already has heavy elections exposure (many House/Senate/governor positions). These factors warrant trading but at a below-baseline size.
Allocation Logic
Sized at $900 — slightly below the $1000 baseline because the edge is modest (7%), liquidity is unknown (zero depth visible), and time to resolution is long (~18 months), which all argue for caution despite the strong structural case.
Entry price: $0.85
Current: $0.88
Status: OPEN
P&L: $31.76