South Carolina · Senate

Who is running?

Annie Andrews (Democratic), Darline Graham (Republican), Kasie Whitener (Libertarian), Mark Hackett (Constitution). The margin below is Annie Andrews minus the other candidate in the main contest; the rest are on the ballot and not in it.

The race, in brief

South Carolina elects a U.S. senator on November 3, 2026. The text calls the state generally a Republican stronghold: Donald Trump won it by 12 points in 2020 and 18 in 2024, and Democrats have not won a Senate election there since 1998. The state profile records a median household income of 66818.0, a white non-Hispanic share of 0.6 and a college share of 0.3.

Four-term senator Lindsey Graham won the June 9 Republican primary with 56.8% and died on July 11. Governor Henry McMaster, on President Trump's recommendation, appointed his sister Darline Graham, a commissioner for the South Carolina Commission for the Blind; she was sworn in on July 14. In the August 11 special primary she led with 32.8% over congressman Ralph Norman's 24.6%, and she won the August 25 runoff 52.4% to 47.6% by the results table (the lead gives 52.5%). The Democratic nominee is pediatrician Annie Andrews, the 2022 nominee for the 1st district, who won 61.5% over Brandon Brown. Libertarian Kasie Whitener and Constitution nominee Mark Hackett are also on the ballot. As of August 5, 2026 Andrews had raised $10,804,041 with $4,119,295 on hand; Graham had raised $346,783 with $251,431 on hand.

All ten raters listed call the race R, among them the Cook Political Report, Inside Elections, Sabato's Crystal Ball and Split Ticket, all dated September 2026. The text's polling average is Graham 45.1%, Andrews 42.5%, or Graham +2.6%; the latest listed poll, Trafalgar Group, a Republican firm (September 23–25), has Graham 43%, Andrews 42%.

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: facts.candidates marks Darline Graham as incumbent: false, but the text says she was appointed and sworn in on July 14 and lists her as the incumbent.; The text gives two figures for the runoff: 52.5% in the lead and 52.4% in the results table.; facts.forecast carries no basis field, so it is not stated whether the model used the statewide polls the text lists.; The Abacus Data poll row (August 26–28, 2026) is garbled in the text and is not reported here.; No rating is finer than 'R'; endorsement sections are empty apart from notes in candidate lists.

Read from the district's section of Wikipedia's state page (CC BY-SA), archived as 90d0c7de46ba; 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

Tim Scott (Republican), in this chamber since 2013, 4 terms, class 3 (term ends 2029). Committees: Senate Committee on Banking, Housing, and Urban Affairs (Chairman); Senate Committee on Finance; Senate Committee on Health, Education, Labor, and Pensions; Senate Committee on Small Business and Entrepreneurship.

Darline Graham (Republican), in this chamber since 2026, 1 term, class 2 (term ends 2027). No committee listed.

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.

The money

FEC bulk candidate summaries through September 30, 2026; $12,124,639 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.

How it has voted for president

A shift of 3.2 points toward the Republicans from 2016 to 2024. county returns summed; 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.

The state in numbers

ACS 5-year state tables; BLS county unemployment and BEA county income, transfers and jobs summed to the state. Every figure is a named column of a named public-domain table, archived before it was read.

Who is ahead, and by how much?

Two numbers because they answer two questions. The nowcast is where opinion stands; the election-day forecast is where it is likely to end up.

How likely is each to win?

Monte Carlo error is ±0.2 points. A change smaller than that is simulation noise rather than news, and this page will not describe it as movement.

How wide is the range?

Nowcast: 90% of simulations fall between -13.0 and +6.3 points. Election day: -16.2 to +6.9. The election-day interval is 3.8 points wider, which is the 33 days of movement still to come.

What is the uncertainty made of?

Total sd 7.34 points, made of race-specific polling error 46%, drift to election day 30%, latent opinion 13%, correlated polling error 11%. The decomposition is stored with the forecast rather than reconstructed, so a probability whose dominant input is a placeholder is visibly that.

What evidence is this built on?

5 polls, most recent 2026-09-25. 17% verified against a primary source.

What changed since the last run?

Shaded band is the 90% interval, line is the central estimate, positive is Annie Andrews ahead of Darline Graham. Over 18 stored forecasts the central estimate moved -3.2 points. There were 7 specification changes (marked on the axis) and 1 new poll arrived over this window — so the movement mixes new evidence with changes to the model.

Since 2026-10-01: margin +0.00 points, win probability +0.0 points, on +0 polls.

Not answered here: why it changed. Splitting a move into new polls, time and specification means re-running the earlier model against the later inputs -- two extra posterior fits -- so it is computed on a cadence (scripts/attribute_forecasts.py) rather than while you wait. This pair of runs has not been decomposed yet. The size of the move is shown; the cause is not guessed at.

How has this model done before?

Measured on 230 forecasts across 230 races in cycles 2016,2018,2020,2022,2024: mean absolute error 4.56 points, Brier score 0.0543. The nominal 90% interval contained the result 94% of the time, the 80% interval 84%, and the 50% interval 47%. Read that with care: a national polling miss moves every race in a cycle at once, so the sample size for a question about the intervals is 5 cycle(s), not 230 forecasts. Per cycle -- bias +1.644 pts; 2016: n=43 bias=+4.68 cov90=0.860; 2018: n=63 bias=-0.52 cov90=1.000; 2020: n=35 bias=+5.44 cov90=0.886; 2022: n=54 bias=-0.60 cov90=0.944; 2024: n=35 bias=+1.48 cov90=1.000.

Where did every number come from?

Nowcast run 2da1e3ca-85ca-44ca-9188-aa09ff9d1f57 and election-day run 9739b4ce-4067-41ff-bcdf-7a845c44ed78, model single_race_latent/0.8.1 at commit bdf7e83107c17a2399efe61a44ef1bbee48f9284, seeds 20260924 and 20260924.