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FORECAST51 DAYS OUT
← Senate3 November 2026 · 51 days out

South Carolina · U.S. Senate

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Darline Graham is narrowly favored to keep South Carolina’s Senate seat in Republican hands. Predicted margin: R+6.8.

Annie Andrews (D)17 in 10017.3%45.6high 50.2 · low 40.9
Darline Graham (R)83 in 10082.7%52.2high 56.9 · low 47.6
Other (O)—2.2
Show all others (2)

Mark Hackett · Kasie Whitener

Other is a combined forecast; individual estimates are not published.

Ballot eligibility alone supplies no quantitative estimate. Other is a collective share, not any named candidate’s forecast. Official ballot sources: Mark Hackett (checked 2026-08-31); Kasie Whitener (checked 2026-08-31).

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

About this field

Sen. Lindsey Graham died July 11, 2026, after winning the GOP nomination. Gov. McMaster appoints an interim senator through January 3; a special Republican primary (Aug 11, runoff Aug 25 if needed) picks the new nominee to face Annie Andrews in November. The seat was already on the 2026 ballot — it now runs as an open 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 R80% range · margin points R+16.3 to D+2.7Open seat

Forecast history

Steady0.0 pts · Sep 11 → Sep 13
EVENAug 1Nov 3 · Election Day

Latest reading · Sep 13 · first published Sep 9 · 80% range · margin points R+16.3 to D+2.7. 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+4.9Used by the forecast: 6 polls (60-day half-life) · measured R+4.9 · after the fitted poll-error shift R+6.47 recorded polls · 7 eligible for the aggregate · 6 with positive weight

FieldworkAddedPollsterResultSample
from 2026-09-083d agoInsiderAdvantage ↗R+1.9D 43.2% · R 45.1%1,200 LV
from 2026-08-26Abacus Data ↗R+13.0D 38% · R 51%306 LV
from 2026-08-18Impact Research ↗EVEND 41% · R 41%700 LV
from 2026-08-143d agoImpact Research (D) ↗D+3.0D 42% · R 39%900 LV
from 2026-06-17Impact Research (D) ↗R+3.0D 45% · R 48%700 LV
from 2026-02-25Impact Research (D) ↗R+5.0D 42% · R 47%700 LV
from 2025-11-21Public Policy Polling (D) ↗314 ActionR+6.0D 36% · R 42%704 Voter type unspecified
Explore poll adjustments

7 of 7 matching · 7 total

Ledger weighted average R+4.9

InsiderAdvantage9 Sep · 1,200 LV · added 10 Sep
Abacus Data28 Aug · 306 LV · added 1 Sep
Impact Research24 Aug · 700 LV · added 31 Aug
Impact Research (D)22 Aug · 900 LV · added 10 Sep
Impact Research (D)22 Jun · 700 LV · added 10 Sep
Impact Research (D)1 Mar · 700 LV · added 10 Sep
Public Policy Polling (D)22 Nov · 704 UNKNOWN · added 10 Sep
Explore all 7 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+11.9
Toward R−18.7
Forecast marginR+6.8

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

All calculations & sources

How this state voted, 2024 −17.870 points

The state's two-party presidential margin in 2024, from our own county sums — the same measurement the model's statewide terrain center is built from. Every pull below is measured from here, not from EVEN, which is why a landslide seat's listed pulls are small numbers and still land where the forecast does.

  • 2024 presidential result for this state, two-party, from Call the Map's own county sums.
  • Same source as Act I's 2024-president reference mark, so the origin lands on it.

Fitted model, above the terrain shown +9.887 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 -7.983 minus starting point -17.870 = 9.887 points.
  • For orientation, the presidential results here: 2024 R+17.9, 2020 R+11.7.
  • The work: the −8.0 D fundamentals push is the sum of the dynamic formula's surviving variables for this race — each one's own contribution is listed below.
  • 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)
  • 9-term formula, held-out validated.

National environment +1.988 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 = +2.0 D 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: +2.0 of this margin.

Structural safeguards −0.424 points

Bounded corrections that keep the model consistent with structural facts.

  • Applied only when a safe state's dynamic fundamentals point in the same direction as its strong presidential lean but are materially compressed toward zero.
  • The 25% correction toward that lean improved safe-race MAE in strict expanding-window validation without changing a historical call.
  • The disclosed adjustment is −0.4 D.

This race’s polls −0.375 points

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

  • 7 matchup-validated, sample/recency/grade-weighted poll(s), latest 2026-09-09
  • InsiderAdvantage (2026-09-09, n=1,200): R+1.9 · weight 1.32
  • Abacus Data (2026-08-28, n=306): R+13.0 · weight 0.45
  • Impact Research (2026-08-24, n=700): ±0.0 · weight 0.60
  • Impact Research (D) (2026-08-22, n=900): D+3.0 · weight 0.63
  • Impact Research (D) (2026-06-22, n=700): R+3.0 · weight 0.07
  • Impact Research (D) (2026-03-01, n=700): R+5.0 · weight 0.00
  • … and 1 more below.
  • Adjusted poll-bank aggregate R+4.9 · 7 recorded polls · 7 eligible for the aggregate · 6 with positive weight. The sealed model records a net polling contribution of −0.4 D. Observation weights are not the final model blend weight. Eligible polls: latest poll: 2026-09-09 (4 days old).
  • Adjusted poll-bank aggregate R+4.9 · 7 recorded polls · 7 eligible for the aggregate · 6 with positive weight; recorded polling contribution −0.4 D. These observation weights must not be read as the model’s final prior-versus-polling weight. Eligible polls: latest poll: 2026-09-09 (4 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.−7.98
National environmentThe national environment’s contribution to the prior. Polling can attenuate its influence; this value is not the national polling margin.+1.99
Structural terrain safeguardA bounded pull toward presidential terrain in heavily partisan states.−0.42
This race's pollsAdmitted head-to-head polls of this race, recency- and quality-weighted.−0.37
Other factors0.00

Recent elections

ElectionResultVotes cast
2020 · U.S. Senate ↗R+10.42,515,104
2014 · U.S. Senate ↗R+19.11,240,075
2008 · U.S. Senate ↗R+15.31,871,431
2002 · U.S. Senate ↗R+10.41,102,912

Margins compare Democratic and Republican vote totals. Nonstandard ballots are labeled separately.

The money

Bar length compares reported receipts in this race; the tick marks cash on hand. A missing filing stays blank rather than becoming $0.

One more fundraising reportCall the Map · $0

The candidates are comfortably out-fundraising the website covering them. A little rude, perhaps, but statistically unsurprising.

Received so far
$0
Measured compute
$26,188.58

Ko-fi and Buy Me a Coffee receipts are counted through Sep 1, 2026. Measured compute prices model runs at standard published API rates; it is not what I paid. Hosting, data and subscriptions, the domain and my own time are not counted. Donations buy gratitude, never a forecast adjustment.

Ko-fi ↗Buy Me a Coffee ↗

See the public support ledger →

Outside spending

Support + opposition · separate from receipts

For and against Annie Andrews$182K

2 spending groups
GroupForAgainst
Security Is Strength PAC$0$176K
RED SENATE$0$6K

For and against Darline Graham$5.4M

12 spending groups
GroupForAgainst
Security Is Strength PAC$2.7M$0
MAGA INC.$828K$0
PALMETTO ACTION$711K$0
AMERICAN MISSION$691K$0
PALMETTO FIRST PAC$0$298K
WFW ACTION FUND INC$100K$0
FREEDOM CAUCUS FUND$0$46K
HOLD THE LINE PAC$0$38K
Gun Rights America$0$7K
NATIONAL RIGHT TO LIFE VICTORY FUND$5K$0
COURAGEOUS CONSERVATIVES PAC$0$5K
RED SENATE$742$0

Includes primary spending. Opposition is recorded against its named target; no benefit to another candidate is assumed.

$13.2M in outside spending on earlier candidates.

No filing matched: Mark Hackett, Kasie Whitener.

FEC filings · through 06/30/2026 · Definitions & method

Race context

Forecast votes cast
1,744,814
Forecast turnout
41.2% of the voting-eligible population
2024 presidential margin
R+18.1

Statewide, 41.9% of the voting-eligible population is projected to cast a ballot; the lower figure above is the share projected to vote in this race.

Population profile Select a measure for its source and denominator

White alone · 65.0%3,342,861 of 5,142,750 · Residents2022 Census · matched race geography
Demographic source and limits

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

Coverage

13 stories · 3 quotes

All coverage and full posts on the Wire →