Scan: Will the Democrats win the South Carolina Senate race in 2026?

date	predicted	market price	confidence
2026-08-27	12%	14%	68%
2026-08-20	9%	11%	62%

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)

What is the current Polymarket YES price for Democrats winning the 2026 South Carolina Senate race, and how has it trended?
Who is the Democratic nominee (or leading candidate) in the 2026 SC Senate race, and how credible/well-funded are they?
Is Lindsey Graham facing a serious Republican primary challenge (e.g., from a Trump-aligned or MAGA challenger), and could a weaker GOP nominee emerge?
What do recent polls of the 2026 SC Senate general election show for the margin between the Republican and Democratic candidates?
What is the historical base rate of Democrats winning statewide federal races in South Carolina (e.g., Graham vs. Harrison 2020 margin, 2024 presidential margin)?
What is the national 2026 midterm environment (generic ballot, presidential approval) and how much could it shift a R+15 to R+20 state?
How do Kalshi and other forecasters (Cook, Sabato, Inside Elections) rate the SC Senate race?

Planner reasoning

South Carolina is a deep-red state where Lindsey Graham is up for re-election in 2026; a Democratic win would require an extraordinary upset, so the key questions are the strength of the Democratic nominee, whether Graham survives a primary (and who replaces him if not), polling, and the national environment. The Polymarket price is the primary anchor, with Kalshi and other Polymarket race markets for triangulation.

2. Research Parallel tool calls

tool	status	time	items	summary
polymarket_direct	OK	0.7s	1	## This Market's Polymarket Data Will the Democrats win the South Carolina Senate race in 2026? - Current price (probability): 14.50% - 7-day price change: +1.00% - 30-day price change: +3.00% - Total volume: $132,523 (USD notional) - Price range: 9.00% - 21.00% - Data points: 90 days
kalshi_related	OK	1.6s	1	1 related markets / summaries. keyword 'South Carolina Senate': ok \| keyword 'Lindsey Graham': no matches
polymarket_related	OK	0.4s	10	Polymarket search over 3 keyword(s), kept 10 matches. keyword 'South Carolina Senate': 5 markets \| keyword 'Lindsey Graham': 0 markets \| keyword 'Senate control 2026': 5 markets
article_search	OK	0.6s	14	Fetched 14 unique articles across 3 queries (lookback=60d). 'South Carolina Senate race 2026 Democratic candidate': 10 articles \| 'Lindsey Graham 2026 primary challenger': 10 articles \| 'South Carolina Senate poll 2026': 10 articles
claude_news	OK	24.3s	15	Here are key findings on the 2026 South Carolina Senate race: - Major development — Lindsey Graham died mid-campaign: Graham's brother, four-term incumbent Lindsey Graham, won the Republican nomination in the June 9 primaries, but died on July 11. His sister was appointed to the seat. (https:
wikipedia	OK	0.2s	3	Fetched 3 Wikipedia entries (0 missing pages).
code_execution	OK	36.5s	0	## Key Findings - Pure presidential-lean baseline (R+18 from 2024): Assuming a D+3 to D+8 midterm environment shift with SD=6–8 pts, model-implied P(Dem win) ranges 0.6% to 10.6%, averaging ~4.2% across the scenario grid. - 2020 Senate-specific baseline (R+10, Graham's margin): Sam

3. Evidence Brief Sonnet 5 · 6273 chars

# Current state The 2026 SC Senate race is a general election between appointed GOP Sen. Darline Graham (sister of late Sen. Lindsey Graham, who died July 11, 2026 shortly after winning the primary) and Democratic nominee Dr. Annie Andrews. Graham won the GOP runoff Aug. 25 with Trump's full endorsement; Andrews won the Dem primary with 61.5%. Polling and ratings show Graham favored by mid-single digits in a state Democrats haven't won a Senate race in since 1998. # Timeline of key events - 2026-06-09: Lindsey Graham wins GOP Senate primary for a 5th term (confirmed, Wikipedia). - 2026-07-11: Lindsey Graham dies unexpectedly (confirmed, Wikipedia/CNN). - 2026-07-14: Darline Graham sworn in to fill her brother's seat after gubernatorial appointment (confirmed, CNBC). - 2026-07-20: Darline Graham announces run for full term with Trump's "Complete and Total Endorsement"; Reps. Ralph Norman and Russell Fry also enter GOP race (confirmed, multiple outlets). - 2026-08-11: Special GOP primary — Graham and Norman advance to runoff, no majority winner (confirmed, AP via CNBC). - 2026-08-25: Graham defeats Norman in GOP runoff, 52.5%–~47.5% (confirmed, Wikipedia/CNBC/NPR); Cook Political Report rates race "Solid R." - 2026-08-25 (concurrent): Annie Andrews confirmed as Democratic nominee with 61.5% over Brandon Brown (confirmed, Wikipedia). - Mid-Sept 2026 (ongoing): National generic ballot moves to D+7.5–9, Trump approval ~38% (reported, Nate Silver/claude_news), but no corresponding SC polling shift reported. - Current (as of research): Pollsmax average shows Graham 47.6% vs. Andrews 43.9%, a 3.7-pt GOP lead across 5 polls (reported, pollsmax.com). # Event Will the Democrats win the 2026 South Carolina U.S. Senate general election (Nov. 3, 2026)? # Outcomes to forecast Yes (Democrat/Andrews wins) / No (Republican/Graham wins) # Kalshi market anchor No kalshi_direct price was returned for this ticker in the research provided. Cross-market Kalshi data exists only for adjacent races (SC Senate 2028-R at 84%, NC Senate 2028-R at 42%), not this contract. Absent a direct anchor, treat Polymarket as the best available live-market proxy. # Resolution source No resolution_source tool result provided; resolution will be AP/Fox/NBC race call or official certification, standard for Senate races. # Sub-question answers 1. **Polymarket YES price/trend** — Current price 14.5%, up +1% (7d) and +3% (30d), range 9–21% over 90 days, $132.5K volume (Polymarket direct). 2. **Democratic nominee** — Dr. Annie Andrews, pediatrician, won primary with 61.5% over Brandon Brown; no evidence of major fundraising/crossover appeal noted in research (Wikipedia, claude_news). 3. **GOP primary dynamics** — Lindsey Graham died before the general; his sister Darline Graham won a competitive runoff (52.5%) against Trump-aligned-but-establishment Rep. Ralph Norman, with Trump's endorsement decisive. She stumbled in debates ("national security is not my thing") but is now the nominee — not a weaker MAGA-vs-establishment fracture, as Trump's pick prevailed (claude_news, CNBC, NPR). 4. **Polling margin** — Pollsmax average: Graham 47.6%, Andrews 43.9% (R+3.7) across 5 polls (claude_news/pollsmax.com). 5. **Historical base rate** — Graham beat Harrison by 10.2 pts in 2020 despite Harrison's $130M raised; Trump won SC by 17.9 pts in 2024; Dems haven't won a SC Senate seat since 1998 (Wikipedia). 6. **National environment** — Generic ballot ~D+7.5-9 nationally, Trump approval ~38%, favoring Dems overall (Nate Silver-cited), but this has not shown up in SC-specific polling shifts per current data. 7. **Race ratings** — Cook Political Report rates SC "Solid R" and does not list it among competitive 2026 pickup targets (Cook, Yahoo/Cook summary). # Key facts (high-confidence, factual) 1. [Wikipedia] Andrews (D) vs. Graham (R) confirmed as general election nominees. 2. [Wikipedia] Trump won SC by 17.9 pts in 2024; Graham beat Harrison by 10.2 pts in 2020. 3. [Cook Political] Race rated "Solid R." 4. [Pollsmax] Current polling average: R+3.7. 5. [Polymarket] Market pricing Dem win at 14.5%. # Cross-market signals - Kalshi related: SC Senate 2028-R priced 84% (different cycle, indicative of enduring GOP lean); no direct 2026 SC Kalshi price found. - Polymarket: 14.5% YES for Dem win here; broader "Dem control of Senate 2026" priced 58.5% YES nationally — implying markets see SC as a non-competitive seat within an otherwise competitive Senate map. - Sportsbook implied: none found. # Analyst opinions and speculation - Code-execution fundamentals model (blending 2024 presidential lean and 2020 Senate result, weighted toward recent rightward drift) estimates Dem win probability ~5–12%, central ~8-10%, roughly consistent with Polymarket's 14.5% (model suggests market may be slightly generous to Dems, or reflects added uncertainty from Graham's death/appointment dynamics). - Buttigieg's SC visits reflect 2028 presidential positioning, not signal about this Senate race's competitiveness. # Directional lean per outcome - **Yes (Dem win)**: Favorable national environment (D+7-9 generic ballot), Andrews outperforming raw partisan lean somewhat in polling (R+3.7 vs. structural ~R+15-18), some chaos from Graham's death/appointment and Darline Graham's shaky debate performance. - **No (GOP hold)**: Deep structural GOP lean (no Dem Senate win since 1998, 2024 pres R+18, 2020 Senate R+10), Trump's full endorsement solidified Graham as nominee, Cook rates "Solid R," polling average still shows clear GOP lead, fundamentals model supports single-digit Dem odds. # Gaps / unknowns - No live Kalshi YES price for this specific ticker was retrieved. - Limited polling sample (only 5 polls in Pollsmax average); unclear house effects/dates of underlying polls. - No direct data on Andrews' fundraising or ad spending versus Harrison's 2020 levels. - Unclear how much sympathy/incumbency effect helps or hurts Darline Graham post-appointment. # Calibration anchors - Polymarket YES price (proxy anchor): 14.5%, trending slightly up. - Fundamentals model estimate: ~5-12% (central ~8-10%). - Historical precedent: Harrison (D) lost by 10.2 pts in 2020 despite $130M raised and closer pre-election polling than currently seen for Andrews.

4. Forecasters 5 draws · Fable 5.1 + GPT-5.6 Sol

claude-fable-5-1

62% conf

Yes	12%
No	88%

No direct Kalshi price exists, so the Polymarket proxy of 14.5% YES is the market anchor. Structural fundamentals are heavily Republican: Trump +17.9 in 2024, Graham +10.2 in 2020 despite Harrison's $130M and similarly close pre-election polls, no Democratic SC Senate win since 1998, and Cook rates the race 'Solid R.' The current R+3.7 polling average across only 5 polls and a strong national environment (D+7-9 generic ballot) keep the Democratic path alive, and Darline Graham's appointment/debate stumbles add some variance, but 2020 showed SC polls overstating Democratic strength by ~7 points. Blending the fundamentals model (~8-10%) with the market's 14.5%, I land slightly below the Polymarket price at ~12%.

claude-fable-5-1

58% conf

Yes	13%
No	87%

No direct Kalshi price exists, so Polymarket's 14.5% YES is the best market anchor, and it sits between the fundamentals model (~8-10%) and a polling average of R+3.7 across only 5 polls. South Carolina's structural lean (Trump +17.9 in 2024, Graham +10.2 over a $130M-funded Harrison in 2020 despite closer pre-election polls) and Cook's 'Solid R' rating argue that SC polling historically overstates Democrats. The favorable national environment (D+7-9 generic ballot, Trump ~38% approval) and Darline Graham's weak debate performances give Andrews a real but modest path, keeping this above the fundamentals floor. I land slightly below the Polymarket proxy at 13%, reflecting the SC polling-error pattern against Democrats.

claude-fable-5-1

62% conf

Yes	14%
No	86%

No direct Kalshi price exists, so the Polymarket proxy at 14.5% (range 9–21% over 90 days) is the best anchor. The Pollsmax average shows Graham +3.7 across five polls, which is closer than the ~R+15-18 structural lean and reflects a strong D+7-9 national environment and Darline Graham's shaky debate performance, but SC polling historically overstates Democrats (Harrison polled near-even in 2020 and lost by 10.2). Cook rates the race Solid R, Trump's endorsement consolidated the GOP nominee rather than fracturing the party, and Democrats haven't won a SC Senate race since 1998; the fundamentals model lands at ~8-10%. I stay near the market at 14%, slightly above fundamentals to reflect the unusual appointed-candidate dynamics and favorable national tide, but well short of a coin flip.

gpt-5.6-sol

74% conf

Yes	13%
No	87%

With no direct Kalshi price available, the 14.5% Polymarket YES price is the best live-market anchor. The R+3.7 polling average and favorable D+7.5–9 national environment give Andrews a credible upset path, but South Carolina's strong Republican baseline, its R+17.9 presidential result in 2024, and Democrats' Senate drought since 1998 weigh heavily against her. Graham has consolidated Republicans with Trump's endorsement, while Cook rates the race Solid R and the fundamentals model places Democratic odds around 5–12%. I therefore price YES slightly below the market proxy at 13%.

gpt-5.6-sol

72% conf

Yes	14%
No	86%

The best live-market proxy is Polymarket's 14.5% Democratic YES price, which is a reasonable anchor given the absence of a direct Kalshi price. Graham leads by 3.7 points in the five-poll average, while the favorable D+7.5–9 national environment and her unusual appointment keep an Andrews upset plausible. However, South Carolina's strong Republican baseline, the GOP's 10.2-point 2020 Senate victory, Trump's 17.9-point 2024 margin, and Cook's Solid R rating all point toward a Republican hold. I therefore stay close to the market while shading Democratic odds slightly downward due to the fundamentals model's lower 5–12% estimate and the lack of evidence that Andrews has exceptional resources or crossover appeal.

6. Final plain mean of 5 draws

13% (66% confidence)

Yes: 13% No: 87%

Mean of 5 draws (0.12, 0.13, 0.14, 0.13, 0.14). No direct Kalshi price exists, so the Polymarket proxy of 14.5% YES is the market anchor. Structural fundamentals are heavily Republican: Trump +17.9 in 2024, Graham +10.2 in 2020 despite Harrison's $130M and similarly close pre-election polls, no Democratic SC Senate win since 1998, and Cook rates the race 'Solid R.' The current R+3.7 polling average across only 5 polls and a strong national environment (D+7-9 generic ballot) keep the Democratic path alive, and Darline Graham's appointment/debate stumbles add some variance, but 2020 showed SC polls overstating Democratic strength by ~7 points. Blending the fundamentals model (~8-10%) with the market's 14.5%, I land slightly below the Polymarket price at ~12%.

Pipeline Timing

Total pipeline time: 103.4s

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