U.S. Senate

Why this race matters

This is the 11th closest Senate race in the forecast, 7.7 points, out of 35.

35 Senate races are on the 2026 ballot in this forecast (15 Democratic leads, 20 Republican leads). Seats that are not on the ballot are not assigned, so this is not a 100-seat chamber.

No earlier forecast of this race is archived, so there is no previous projection, date, or reason to show.

History block in the model: R+16.4. That is the office blend, not one past election.

Last same-office result in the candidate file: 2022 R+25.9. A special on the 2026 ballot is not automatically that contest.

Polling block: R+3.3. The published result is still the county sum.

Counties

Every reporting unit in the race. Tap a county to open its precincts. The projected votes above are this table added up. They are not ballots cast.

Counties

County	Leader	Party	Margin	Vote share	Projected ↓
Greenville County	RDarline Graham, RDarline Graham	R	R+12.6	55.6%	181,815
Charleston County	DAnnie Andrews, DAnnie Andrews	D	D+15.3	56.9%	148,123
Horry County	RDarline Graham, RDarline Graham	R	R+28.9	63.8%	142,207
Richland County	DAnnie Andrews, DAnnie Andrews	D	D+44.2	71.4%	125,952
Spartanburg County	RDarline Graham, RDarline Graham	R	R+24.0	61.3%	107,437
York County	RDarline Graham, RDarline Graham	R	R+9.5	54.0%	103,613
Lexington County	RDarline Graham, RDarline Graham	R	R+23.8	61.2%	101,433
Berkeley County	RDarline Graham, RDarline Graham	R	R+6.7	52.6%	77,910
Beaufort County	RDarline Graham, RDarline Graham	R	R+4.9	51.7%	72,088
Anderson County	RDarline Graham, RDarline Graham	R	R+37.7	68.2%	67,872
Aiken County	RDarline Graham, RDarline Graham	R	R+16.3	57.4%	59,444
Dorchester County	RDarline Graham, RDarline Graham	R	R+5.0	51.8%	53,694
Florence County	DAnnie Andrews, DAnnie Andrews	D	D+1.6	50.1%	42,216
Pickens County	RDarline Graham, RDarline Graham	R	R+43.0	70.8%	41,740
Lancaster County	RDarline Graham, RDarline Graham	R	R+15.1	56.9%	37,581
Sumter County	DAnnie Andrews, DAnnie Andrews	D	D+14.5	56.5%	31,189
Oconee County	RDarline Graham, RDarline Graham	R	R+41.9	70.3%	29,182
Georgetown County	RDarline Graham, RDarline Graham	R	R+9.9	54.2%	26,068
Orangeburg County	DAnnie Andrews, DAnnie Andrews	D	D+34.2	66.4%	25,527
Kershaw County	RDarline Graham, RDarline Graham	R	R+18.6	58.6%	23,154
Greenwood County	RDarline Graham, RDarline Graham	R	R+19.4	59.0%	21,327
Darlington County	RDarline Graham, RDarline Graham	R	R+3.7	51.1%	20,943
Laurens County	RDarline Graham, RDarline Graham	R	R+25.9	62.2%	15,125
Cherokee County	RDarline Graham, RDarline Graham	R	R+36.4	67.5%	12,435
Colleton County	RDarline Graham, RDarline Graham	R	R+4.9	51.7%	10,096
Jasper County	DAnnie Andrews, DAnnie Andrews	D	D+3.6	51.1%	10,068
Chesterfield County	RDarline Graham, RDarline Graham	R	R+13.1	55.8%	9,207
Newberry County	RDarline Graham, RDarline Graham	R	R+19.4	59.0%	9,076
Clarendon County	DAnnie Andrews, DAnnie Andrews	D	D+1.0	49.8%	9,015
Chester County	RDarline Graham, RDarline Graham	R	R+3.9	51.3%	8,593
Marion County	DAnnie Andrews, DAnnie Andrews	D	D+23.8	61.2%	7,395
Williamsburg County	DAnnie Andrews, DAnnie Andrews	D	D+35.0	66.8%	7,173
Edgefield County	RDarline Graham, RDarline Graham	R	R+16.9	57.7%	6,968
Dillon County	DAnnie Andrews, DAnnie Andrews	D	D+2.4	50.5%	6,552
Fairfield County	DAnnie Andrews, DAnnie Andrews	D	D+26.5	62.5%	6,195
Union County	RDarline Graham, RDarline Graham	R	R+17.7	58.2%	6,152
Abbeville County	RDarline Graham, RDarline Graham	R	R+27.4	63.0%	6,031
Marlboro County	DAnnie Andrews, DAnnie Andrews	D	D+15.6	57.1%	5,608
Barnwell County	RDarline Graham, RDarline Graham	R	R+2.3	50.4%	5,415
Hampton County	DAnnie Andrews, DAnnie Andrews	D	D+19.7	59.1%	4,548
Saluda County	RDarline Graham, RDarline Graham	R	R+29.4	64.0%	4,512
Lee County	DAnnie Andrews, DAnnie Andrews	D	D+30.9	64.8%	4,461
Calhoun County	RDarline Graham, RDarline Graham	R	R+1.1	49.8%	4,372
McCormick County	RDarline Graham, RDarline Graham	R	R+3.9	51.2%	3,399
Bamberg County	DAnnie Andrews, DAnnie Andrews	D	D+28.5	63.6%	3,145
Allendale County	DAnnie Andrews, DAnnie Andrews	D	D+59.7	79.1%	1,513

Model

1. Raw data

   2024 presidential baseline

   National R−D 1.5

   County presidential file. Not the 2026 result.

2. Raw data

   Generic ballot

   D 51.7 R 43.1 R−D -8.6

   National Wikipedia aggregate, 2026-10-30. State generic ballots, where a public poll exists, are mixed with the national swing for a race that does not have its own poll: ME, MI, NH, NY, OH. A state with no generic-ballot poll keeps the national swing and is not assigned a neighbor's.

3. Raw data

   Party identification

   Pew D+5 and Gallup D+10, blend R−D -7.3

   Pew NPORS 2026, identifiers plus leaners: Republican 43, Democratic 48. Gallup party identification plus leaners, first two quarters of 2026: Democratic 49, Republican 39. Pew is 55% of this blend and Gallup is 45%.

4. Model input

   National block

   R−D -8.1

   60% generic ballot and 40% party identification. The swing versus the 2024 presidential margin is what gets transmitted.

5. Model input

   Swing transmitted

   1.30 × -9.5 = -12.4

   This race has its own poll. The swing in the history blocks, before they shrink toward that poll, is the national block minus the 2024 presidential margin. Elasticity is shrunk halfway toward 1.

6. Model input

   History block

   R−D 16.4

   Weights 2018 5 / 2024 35 / 2020 20 / 2022 40. If that office was on the ballot in 2022, that year takes the 40 and 2018 takes the 5. Otherwise 2018 keeps the 40. A missing year is filled with the 2020 result for the same office. Another office is not used. The year lines are Greenville County, the largest county, not the state total: 2018 from 2020 R+14.6 w5, 2024 from 2020 R+14.6 w35, 2020 R+14.6 w20, 2022 R+30.2 w40. The state number above is the vote-weighted sum. A 2024 county map is not copied forward unchanged.

7. Model input

   Electorate block

   R−D 6.5

   History reweighted by usual midterm turnout, plus half of the transmitted swing. Rural and presidential-only counties still move farther when the result is spread back to counties. That spread is ballot size, not the demographic file. Published ballots are the 2018 midterm canvass for this office, split by these modeled shares. They are not the 2024 presidential vote. The 2026 early-vote count is not inside this margin.

8. Model input

   Turnout block

   R−D 10.5

   Each county is weighted by its 2018 ballots divided by its 2024 presidential ballots. Small counties shrink halfway toward the state median. 2020 mail shares are not used.

9. Model input

   National environment

   R−D 3.4

   History plus the full transmitted swing. With no poll of this race, that swing is the state generic ballot mixed with the national block, or the national block alone.

10. Model input

    State environment

    R−D 7.9

    History plus 45 percent of the transmitted swing. This is a Senate and governor weight.

11. Model input

    State partisan lean

    R−D 17.9

    The 2024 presidential margin of this state, or of this district for a House race. It is heavier than the old state-environment block and is not shrunk toward the polling term.

12. Model input

    Trump popularity

    R−D -4.1

    New York Times approval average, October 29, 2026: 37.4% approve, 60.2% disapprove. Net approval -22.800000000000004. That is not a vote share. Four-tenths of the net is a margin, then scaled by this place's partisan lean (factor 0.45), so an unpopular president costs more in a Democratic state.

13. Model input

    Candidate favorability

    R−D 0.0

    Darline Graham's 2020 race is already in the history block, so it is not applied again as favorability.

14. Model input

    Demographics

    R−D 2.1

    One statewide block only. A county that is more college-educated or more nonwhite than the other counties in this race takes more of the transmitted swing, and a more rural county takes less. That changes this block, at its weight. It does not choose which counties move when the margin is spread back out. That spread uses ballot size. The shares are the 2012–2016 American Community Survey and the 2010 Census, from the 2018 county election-context file. Alaska is not in that file.

15. Model input

    Finance

    R−D 11.5

    No sourced spending edge. The block is history, or history shrunk toward the poll. It is not a finance model.

16. Model input

    Issues

    R−D 11.5

    No sourced issue score. Same treatment as finance. It is not a separate issue model.

17. Model input

    Polling

    R−D 2.3

    Individual polls 2.4 (80%) and the Wikipedia average 1.6 (20%). Named support R−D 1.7. Allocated support R−D 2.3. Named support does not move. Only the undecided line is split, 54.5% Republican and 45.5% Democratic. That is the 2024 two-party Republican share 59.1 moved halfway to 50 and capped at 60/40. A minor-party line is not published as its own candidate. Banned individual rows excluded: 0. No same-office polling miss was sourced, so none is added. Applied to the polling term: 0.00. Public pollsters: 4. Outliers: 1. Recency half-life 16 days. Sample weight n/(n+350). A registered-voter poll is 0.90. An internal poll, or a poll sponsored by one party, is weighted 0. It is not in the average. An internal-only file is dropped. A poll that names both parties is not an internal. A poll more than 8 points from the median of the others is cut in half. Pollster quality nudges that weight by only a few percent. The same rule is used on a House poll. House district polls are likely-voter polls only.

18. Model input

    Generic ballot weight

    R−D 3.3

    The generic ballot stays in the blend next to the independent polls. It is not shrunk toward the poll and an internal does not replace it. Weight 9.5%.

19. Model input

    Top line

    Not a House term

    Senate and governor are the top line. They are not moved by themselves.

20. Model input

    Candidate

    R+0.75 added whole

    Darline Graham was appointed and has not won the seat, so the incumbent term is half, 0.75. Overperformance is a separate term and is not added again here. Darline Graham's 2020 race is already in the history block, so it is not applied again. These points are not watered down to the candidate weight. The candidate weight is a separate slice of the baseline. On a Senate or governor race with three public polls and no outlier, the points stop at that poll instead of moving past it.

21. Model input

    Scandal

    None

    No candidate on this ballot is scandal-defined.

22. Model input

    Endorsements

    R−D +0.27

    Trump endorsed Darline Graham. The presidential lean here is R−D 17.9, so the endorsement helps 0.27. Ballotpedia, Endorsements by Donald Trump, 2026 tables, page updated August 5, 2026. A primary endorsement is counted when that person is the nominee. A lost primary, a candidate not on the ballot, and a withdrawn endorsement are not.

23. Model input

    Halfway floor

    Not applied

    Not applied. At least three public polls from different pollsters are not outliers. An outlier elsewhere in the file is already cut in half and does not put the floor back on.

24. Model input

    Pooling

    35% of the way from each history block toward the polling term

    Otherwise the shrink is 35%.

25. Model input

    Prediction market

    72% win probability

    Darline Graham 72.0% is a win probability, not a vote share. Republican win probability 72.0 from Kalshi 71.5% Republican; Polymarket 72.5% Republican. A price of 50 is a tie. Each point above 50 is 0.35 margin points, capped at 12, so the raw margin is 7.7. That margin is shrunk 40% toward the pre-market margin 7.0, which leaves 7.4. It enters once, at 2.5%. The polling term is not nudged. The market and the polls differ by more than 15 points of win probability, so the weight is half of 5% and the interval is wider.

26. Model input

    State bend

    None

    Not applied.

27. Model input

    State environment adjustment

    R−D -0.3

    The 2022 statewide margin was R−D 17.4 and the 2024 presidential margin was R−D 17.9. The country moved 1.4 from that presidential vote to the 2022 House vote. Fifteen percent of the difference is kept, capped at 1.5, so the state environment is -0.3 on top of the national swing.

28. Model input

    Early vote

    D+0.3

    No party is on the file. Ballots that match a 2024 presidential county sit at R−D 15.6. The 2024 vote in the same counties was R−D 17.9. The early mix is D+2.2 relative to that vote. Fifteen percent is kept, capped at 1, so D+0.3. This is where the ballots were cast. A more college-educated or more nonwhite county still takes more of the national swing in the demographics block, and a more rural county takes less. That block is separate from this point. This is not a count of how anyone voted, and not another model's estimate of the electorate.

29. Model input

    Other ratings

    R−D 5.6 at 3.0%

    Cook, Sabato, Inside Elections, and the other columns on the same published tables (Decision Desk HQ, RealClearPolitics, Split Ticket, FiftyPlusOne, The Economist, Fox News, Silver Bulletin). 10 ratings, average R−D 5.6. A toss-up is 0, tilt 1.5, lean 3.5, likely 7, safe or solid 12. If this race is already further to that side, the rating does not pull it back. Mixed in after everything else, at 3.0 percent. It does not replace the poll. A seat nobody has rated is left alone.

30. Model input

    Weights

    polling 21.3% · generic 9.0% · stateLean 14.5% · trump 9.6% · favorability 8.9% · history 6.4% · candidate 4.8% · national 4.8% · electorate 4.0% · stateEnv 3.2% · turnout 2.4% · demographics 2.4% · finance 1.6% · issues 1.7% · market 2.4% · ratings 3.0%

    History is lighter. State partisan lean, Trump popularity, and candidate favorability are their own terms. A market, when it qualifies, scales every other weight and is not taken out of polling alone. Published ratings, when a race has them, are mixed in after that. They are not taken out of polling alone.

31. County-sum margin

    7.7

    This is the sum of the county projections. Counties are not moved afterward to force this total.

32. Minor parties

    None

    Other is the 2024 presidential vote that was neither Democratic nor Republican, weighted by these counties. It is not the last forecast. A missing opponent is not Other. No Libertarian, Green, Constitution, or other minor line was on this ballot.

33. 80% interval

    -3.0 to 18.4

    10th to 90th percentile of 50,000 draws. Poll, national, state, turnout, and candidate error.

34. 95% interval

    -8.7 to 24.0

    2.5th to 97.5th percentile. Senate and governor state errors in the same state share a correlation of 0.30. The band shown is the marginal interval.