Scan: Will the Democrats win the New Hampshire Senate race in 2026?

date	predicted	market price	confidence
2026-08-29	85%	86%	67%
2026-08-22	86%	89%	68%

1. Planner Fable 5.1 · Fermi decomposition + tool plan

Tools chosen: polymarket_direct kalshi_related polymarket_related article_search claude_news wikipedia code_execution

Sub-questions (Fermi decomposition)

Who are the confirmed/likely Democratic and Republican nominees for the 2026 NH Senate race, and has any high-profile Republican (e.g., John E. Sununu, Scott Brown) entered or declined?
What do recent public polls show for the general election matchup (e.g., Pappas vs. Brown or Sununu), and what is the polling margin trend?
What is the current national political environment (generic congressional ballot, presidential approval) heading into the 2026 midterms, and does it favor the out-party Democrats?
What is the historical base rate of Democrats winning NH federal Senate races in the last 20 years and in midterm years under a Republican president?
How do forecasters (Cook, Sabato, Inside Elections) currently rate the NH Senate race?
What are the current Polymarket and Kalshi prices for a Democratic win, and do they diverge?

Planner reasoning

This is a 2026 New Hampshire open-seat Senate race (Jeanne Shaheen retiring). Key drivers: candidate field (Chris Pappas vs. Scott Brown / John Sununu-type GOP recruit), polling, national environment/generic ballot, and NH's Democratic federal lean despite GOP state-level strength. Market prices on Polymarket and Kalshi are the primary anchors; news and background fill in the candidate and polling picture.

2. Research Parallel tool calls

tool	status	time	items	summary
polymarket_direct	OK	0.2s	1	## This Market's Polymarket Data Will the Democrats win the New Hampshire Senate race in 2026? - Current price (probability): 84.00% - 7-day price change: +1.00% - 30-day price change: -1.50% - Total volume: $70,958 (USD notional) - Price range: 81.00% - 89.50% - Data points: 89 days
kalshi_related	OK	3.5s	2	2 related markets / summaries. keyword 'New Hampshire Senate': ok \| keyword 'Pappas': no matches \| keyword 'Sununu Senate': ok
polymarket_related	OK	0.2s	0	Scanned 100 active Polymarket markets, kept 0 matches. keyword 'New Hampshire Senate': 0 markets \| keyword 'Senate control 2026': 0 markets \| keyword 'Pappas': 0 markets
article_search	OK	0.8s	12	Fetched 12 unique articles across 4 queries (lookback=60d). 'New Hampshire Senate race 2026 Pappas': 10 articles \| 'John Sununu Senate run New Hampshire': 10 articles \| 'Scott Brown Senate 2026 New Hampshire poll': 10 articles \| 'Cook Political Report Senate ratings New Hampshire': 10 articles
claude_news	OK	24.0s	17	## Findings: 2026 New Hampshire Senate Race - Candidates confirmed after Sept 8, 2026 primaries: Democratic Rep. Chris Pappas and Republican former senator John Sununu are the nominees for their respective parties , after Pappas won the Democratic nomination with 65% of the vote against medic
wikipedia	OK	0.2s	4	Fetched 4 Wikipedia entries (0 missing pages).
code_execution	OK	34.9s	0	## Base Rates: NH U.S. Senate (2002–2022) - Democrats won 5 of 8 races (62.5%): R–Sununu 2002 (+4.5), R–Gregg 2004 (+36, uncontested-ish landslide), D–Shaheen 2008 (+7), R–Ayotte 2010 (+23), D–Shaheen 2014 (+3.5), D–Hassan 2016 (+0.1, razor-thin), D–Shaheen 2020 (+16), **D–Hassa

3. Evidence Brief Sonnet 5 · 5805 chars

# Current state The Democratic (Chris Pappas) and Republican (John Sununu) nominees were set after the September 8, 2026 primaries; the general election is set for November 3, 2026 to fill retiring Sen. Jeanne Shaheen's open seat. Polling since the primary has been mixed-to-favorable for Pappas, and Democrats hold a "modest favorite" rating, but the race remains genuinely competitive. # Timeline of key events - 2026-01-21 (confirmed, UNH poll): Sununu led Brown for GOP nomination; Pappas led both potential GOP rivals in general-election matchups. - 2026-02 (confirmed): Trump endorsed Sununu for the GOP nomination. - ~2026-08 (reported): Kamala Harris endorsed Pappas. - 2026-08-26 (reported, UNH poll): Sununu led Pappas 45%–43%, a reversal from an earlier Pappas lead of 47%–44%. - 2026-09-08 (confirmed): Primaries held — Pappas won Democratic nomination (65% vs. Karishma Manzur); Sununu won GOP nomination (68.5% vs. Scott Brown). - 2026-09-08 to 09-10 (reported, Rasmussen poll): Pappas led Sununu 45%–34% (11 points) among likely voters, taken just after the primary. - Ongoing (reported): Cook Political Report/Sabato's Crystal Ball rate the race "Lean Democratic"; Inside Elections rates it "Tilt Democratic" (ratings as of pre-primary/mid-2026, likely still current). # Event Will the Democrats (Chris Pappas) win the 2026 New Hampshire U.S. Senate race against Republican John Sununu? # Outcomes to forecast - Yes (Democrats/Pappas win) - No (Republicans/Sununu win) # Kalshi market anchor No direct kalshi_direct price was returned in this data pull; the ticker itself is the event ID given. Polymarket's equivalent contract prices **Yes at 84%** (7d: +1%, 30d: −1.5%; range 81–89.5%; $70,958 volume over 89 days) — treat this as the closest live cross-market anchor absent a native Kalshi quote. A related Kalshi 2028 NH Senate market (different cycle) prices GOP at only 9%, consistent with a broader Democratic lean in the state. # Sub-question answers 1. **Nominees/entrants**: Confirmed — Chris Pappas (D) and John Sununu (R) are the nominees after the 2026-09-08 primaries; Scott Brown lost the GOP primary to Sununu 68.5%–~24% [Wikipedia, CBS, CNN]. 2. **Polling**: Mixed — UNH (8/26) had Sununu +2 (45-43); Rasmussen (9/8-10, post-primary) had Pappas +11 (45-34); Emerson showed a statistical tie; January UNH poll had Pappas leading in general-election matchups [claude_news, Cook Political]. 3. **National environment**: Favors Democrats — generic ballot ~D+6.5-6.6 (Nate Silver average), Trump approval at record lows, economic/Iran war concerns cited as headwinds for GOP [thehill.com, nbcnews.com, natesilver.net]. 4. **Historical base rate**: Democrats won 5 of 8 NH Senate races 2002-2022 (62.5%); in midterm years specifically, 2/4 (50%), but NH has voted Democratic for president in all 5 cycles since 2008 (avg +5.1 margin) [code_execution]. 5. **Forecaster ratings**: Cook Political Report and Sabato's Crystal Ball rate it "Lean Democratic"; Inside Elections rates it "Tilt Democratic" [claude_news, cookpolitical.com]. 6. **Cross-market prices**: Polymarket Yes = 84%; no distinct native Kalshi quote for this specific ticker was returned, though a related 2028-cycle NH Senate market shows GOP at just 9% [polymarket_direct, kalshi_related]. # Key facts (high-confidence, factual) 1. [Wikipedia] Pappas (D) and Sununu (R) are official nominees; election is Nov 3, 2026. 2. [Wikipedia] This is the first open NH Senate seat since 2010; Republicans haven't won an NH Senate race since 2010. 3. [Ballotpedia] NH has been a GOP trifecta (governor + legislature) since 2021 despite voting Democratic federally. 4. [claude_news/Cook] Consensus ratings: Lean/Tilt Democratic. 5. [code_execution] NH presidential margin has favored Democrats in all 5 cycles since 2008 (avg +5.1). # Cross-market signals - Kalshi related: 2028-cycle NH Senate (GOP) priced at 9% — signals durable structural Dem lean, though different election year. - Polymarket: Yes (Dem win) = 84%, stable/slightly down over 30 days, modest volume (~$71k). - Sportsbook implied: none available. # Analyst opinions and speculation - Cook Political Report: notes it's "hard to see Republicans pulling off the upset" given tough midterm environment, but acknowledges Emerson tie poll and GOP belief that any Sununu family member polls competitively. - NBC/Hill: Republicans still optimistic due to Sununu's family political brand and prior Senate tenure; Democrats banking on Trump approval weakness and economic dissatisfaction. # Directional lean per outcome - **Yes (Dem win)**: Favorable national environment (D+6-7 generic ballot), NH's consistent blue lean at federal level, favorable forecaster ratings (Lean/Tilt D), post-primary Rasmussen poll showing +11 Pappas, historical base rate ~62.5% Dem Senate wins, Polymarket at 84%. - **No (GOP win)**: UNH poll showed Sununu +2 just before primary; Emerson tie; Sununu's strong name-brand/family legacy in NH; NH's statewide GOP trifecta shows non-federal conservative lean; historical midterm-year Dem win rate only 50%; race is single-digit margin historically prone to upsets (2002, 2016 razor-thin). # Gaps / unknowns - No native Kalshi YES price was returned for this exact ticker — Polymarket (84%) used as best available anchor. - No most-recent (October/pre-election) polling included; data ends ~mid-September. - No info on fundraising, ad spending, or debate performance post-primary. # Calibration anchors - Polymarket cross-market price: 84% Yes (proxy anchor in absence of direct Kalshi quote). - Historical base rate: Dems won 5/8 (62.5%) NH Senate races 2002-2022; won NH at presidential level 5/5 since 2008. - Fundamentals model (code_execution): ~73-84% probability range for Dem win given current environment assumptions.

4. Forecasters Fable 5.1 + GPT-5.6 Sol · in parallel

claude-fable-5-1

55% conf

Yes	81%
No	19%

The closest live anchor is Polymarket at 84% Yes, consistent with Lean/Tilt Democratic ratings from Cook, Sabato, and Inside Elections and a national environment around D+6.5 on the generic ballot with weak Trump approval. NH's federal-level blue lean (Dems won presidential contests all five cycles since 2008; no GOP Senate win since 2010) supports Pappas, and the post-primary Rasmussen poll showed him +11. However, the UNH Sununu +2 and Emerson tie polls, plus the Sununu family brand and NH's GOP trifecta at the state level, mean the race is genuinely competitive, so I shade slightly below the market to ~81%.

gpt-5.6-sol

68% conf

Yes	82%
No	18%

The confirmed Pappas-Sununu matchup modestly favors Yes because Democrats have stronger recent federal performance in New Hampshire, while Sununu remains a credible challenger with a strong political brand. Polling points toward a Democratic edge but substantial uncertainty: Pappas led Rasmussen by 11 points, while UNH had Sununu ahead by 2 and Emerson found a statistical tie. The D+6.5 national environment and unanimous Lean/Tilt Democratic ratings support Yes, although the state's GOP trifecta prevents treating the race as safe. I place Yes at 82%, slightly below the 84% Polymarket proxy anchor, because the polling is heterogeneous and the brief lacks late-campaign polling, fundraising, and debate evidence.

5. Devil's Advocate Sonnet 5 · red-team critique

Both forecasts anchor almost entirely on Polymarket (84%) and barely interrogate whether that price itself is well-calibrated — given only ~$71k volume over 89 days, this is a thin, low-liquidity market that could be stale or susceptible to a few large traders, yet neither forecaster discounts for anchor reliability beyond a token 2-4 point haircut.

Neither forecaster grapples with the "Gaps/unknowns" note that data ends ~mid-September with no October/pre-election polling — given the close time is Nov 3, nearly two months of campaign dynamics (ads, debates, fundraising, potential Trump-driven news shocks) are unaccounted for, which should arguably widen uncertainty rather than just be mentioned in passing.

Both treat the midterm-year historical base rate loosely: the brief specifically notes Dems won only 2/4 (50%) NH Senate races in midterm years specifically, which is far more pessimistic for Yes than the overall 62.5% figure both rationales implicitly lean on — this distinction is glossed over.

The Rasmussen +11 post-primary poll is given significant weight by both forecasters despite Rasmussen's well-documented partisan-lean/methodological reputation issues in forecasting circles; treating it as comparable evidence to UNH/Emerson without discounting for pollster quality is a reference-class error.

Neither forecast meaningfully addresses the tail scenario where the "genuinely competitive" framing (Cook's own hedge, Emerson tie, UNH Sununu+2) combined with Sununu's name-brand strength could represent a systematic polling-error risk analogous to 2002/2016 "razor-thin" NH Senate races explicitly flagged in the brief — both converge to nearly identical 81-82% figures without exploring how a 2016-style late break to the GOP would materially change the calculus.

Both forecasters cite the "GOP trifecta" fact as a minor headwind but don't reconcile why NH's strong state-level conservative lean coexists with confident federal Dem projections — this tension deserves more than a passing mention, since it could signal down-ballot Republican strength that Senate-level fundamentals models may underweight.

6. Aggregator Fable 5.1 · final calibrated forecast

80% (62% confidence)

Yes: 80% No: 20%

Both forecasts converge near 81-82% Yes, slightly below the 84% Polymarket anchor, and the sub-question evidence (Lean/Tilt Democratic ratings, D+6.5 generic ballot, NH's consistent federal blue lean, no GOP Senate win since 2010) supports a solid Democratic favorite. The critique correctly flags the thin Polymarket liquidity and the absence of October polling, which argues for modestly wider uncertainty, but the Rasmussen concern cuts the other way: a Pappas +11 from a GOP-leaning pollster is, if anything, favorable for Yes. The UNH Sununu +2 and Emerson tie polls plus the Sununu family brand keep a genuine ~1-in-5 upset path alive, consistent with NH's history of razor-thin Senate races. I settle at 80% Yes, a small haircut from the market for anchor reliability and stale data, without moving beyond both forecasts since the critique exposed no shared directional flaw.

Pipeline Timing

Total pipeline time: 111.4s

Per-tool research timings shown in the Research section above.