U.S. Senate

Why this race matters

This is the 12th closest Senate race in the forecast, 8.1 points, out of 35.

The published margin is the leader over the next candidate. The opponent is not the other major party, so this race is not treated as a Republican-minus-Democrat swing.

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 incumbent is on the ballot.

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+3.2. That is the office blend, not one past election.

Last same-office result in the candidate file: 2024 R+7.1. A special on the 2026 ballot is not automatically that contest.

Polling block: R+16.0. 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 ↓
Yellowstone County	RKurt Alme, RKurt Alme	R	R+13.4	47.8%	69,685
Missoula County	ISeth Bodnar, ISeth Bodnar	I	+17.2	45.5%	62,305
Gallatin County	ISeth Bodnar, ISeth Bodnar	I	+4.9	41.0%	59,844
Flathead County	RKurt Alme, RKurt Alme	R	R+19.3	51.5%	54,058
Lewis and Clark County	ISeth Bodnar, ISeth Bodnar	I	+1.2	39.7%	35,978
Cascade County	RKurt Alme, RKurt Alme	R	R+8.0	44.3%	32,177
Ravalli County	RKurt Alme, RKurt Alme	R	R+22.8	53.7%	25,603
Silver Bow County	ISeth Bodnar, ISeth Bodnar	I	+16.2	45.2%	15,605
Lake County	RKurt Alme, RKurt Alme	R	R+8.2	44.4%	14,478
Lincoln County	RKurt Alme, RKurt Alme	R	R+32.2	59.7%	10,093
Park County	RKurt Alme, RKurt Alme	R	R+2.6	40.9%	10,032
Jefferson County	RKurt Alme, RKurt Alme	R	R+18.6	51.1%	7,099
Sanders County	RKurt Alme, RKurt Alme	R	R+30.9	58.9%	6,908
Carbon County	RKurt Alme, RKurt Alme	R	R+17.2	50.2%	6,248
Hill County	RKurt Alme, RKurt Alme	R	R+1.0	39.9%	5,825
Fergus County	RKurt Alme, RKurt Alme	R	R+30.2	58.5%	5,747
Madison County	RKurt Alme, RKurt Alme	R	R+25.6	55.5%	5,532
Stillwater County	RKurt Alme, RKurt Alme	R	R+36.1	62.2%	5,057
Custer County	RKurt Alme, RKurt Alme	R	R+24.6	54.9%	4,964
Beaverhead County	RKurt Alme, RKurt Alme	R	R+23.5	54.2%	4,960
Richland County	RKurt Alme, RKurt Alme	R	R+38.9	64.0%	4,545
Glacier County	ISeth Bodnar, ISeth Bodnar	I	+23.0	47.6%	4,347
Deer Lodge County	ISeth Bodnar, ISeth Bodnar	I	+12.2	43.7%	4,170
Broadwater County	RKurt Alme, RKurt Alme	R	R+33.5	60.5%	4,118
Dawson County	RKurt Alme, RKurt Alme	R	R+33.7	60.7%	3,970
Big Horn County	ISeth Bodnar, ISeth Bodnar	I	+10.3	43.0%	3,827
Valley County	RKurt Alme, RKurt Alme	R	R+24.6	54.9%	3,492
Roosevelt County	ISeth Bodnar, ISeth Bodnar	I	+1.7	39.9%	2,681
Rosebud County	RKurt Alme, RKurt Alme	R	R+18.5	51.0%	2,530
Teton County	RKurt Alme, RKurt Alme	R	R+24.9	55.1%	2,214
Powell County	RKurt Alme, RKurt Alme	R	R+28.7	57.5%	2,038
Chouteau County	RKurt Alme, RKurt Alme	R	R+14.2	48.3%	2,010
Blaine County	ISeth Bodnar, ISeth Bodnar	I	+6.9	41.8%	1,874
Musselshell County	RKurt Alme, RKurt Alme	R	R+45.4	68.1%	1,870
Pondera County	RKurt Alme, RKurt Alme	R	R+21.2	52.7%	1,770
Mineral County	RKurt Alme, RKurt Alme	R	R+26.5	56.1%	1,758
Sweet Grass County	RKurt Alme, RKurt Alme	R	R+34.0	60.9%	1,478
Phillips County	RKurt Alme, RKurt Alme	R	R+40.0	64.7%	1,359
Granite County	RKurt Alme, RKurt Alme	R	R+25.0	55.1%	1,351
Toole County	RKurt Alme, RKurt Alme	R	R+33.6	60.6%	1,270
Sheridan County	RKurt Alme, RKurt Alme	R	R+22.9	53.8%	1,187
Fallon County	RKurt Alme, RKurt Alme	R	R+47.3	69.3%	935
Judith Basin County	RKurt Alme, RKurt Alme	R	R+34.9	61.4%	840
Meagher County	RKurt Alme, RKurt Alme	R	R+34.2	61.0%	728
Powder River County	RKurt Alme, RKurt Alme	R	R+47.8	69.7%	686
Wheatland County	RKurt Alme, RKurt Alme	R	R+34.6	61.3%	674
McCone County	RKurt Alme, RKurt Alme	R	R+48.1	69.8%	672
Liberty County	RKurt Alme, RKurt Alme	R	R+29.9	58.2%	613
Daniels County	RKurt Alme, RKurt Alme	R	R+39.1	64.1%	591
Carter County	RKurt Alme, RKurt Alme	R	R+53.4	73.2%	530
Garfield County	RKurt Alme, RKurt Alme	R	R+59.2	76.9%	497
Prairie County	RKurt Alme, RKurt Alme	R	R+37.9	63.5%	427
Wibaux County	RKurt Alme, RKurt Alme	R	R+42.8	66.4%	339
Golden Valley County	RKurt Alme, RKurt Alme	R	R+43.4	66.9%	320
Treasure County	RKurt Alme, RKurt Alme	R	R+39.8	64.6%	274
Petroleum County	RKurt Alme, RKurt Alme	R	R+50.7	71.6%	201

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 3.2

   Weights 2018 40 / 2024 35 / 2020 20 / 2022 5. 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 Yellowstone County, the largest county, not the state total: 2018 R+3.5 w40, 2024 R+16.2 w35, 2020 R+17.2 w20, 2022 from 2020 R+17.2 w5. 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 8.2

   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 10.7

   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 5.9

   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 8.6

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

11. Model input

    State partisan lean

    R−D 19.9

    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

    Open seat or no incumbent. Favorability is zero.

14. Model input

    Demographics

    R−D 4.8

    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 10.9

    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 10.9

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

17. Model input

    Polling

    R−D 16.0

    Three-way ballot. Weighted named shares D 17.8, R 42.5, independent 28.1. The polling term is the lead of the first over the second, R+14.4, not Republican minus the candidate the independent replaced. The two-party Wikipedia extract drops that independent and is not the margin. The same-office polling miss is still added. Named support does not move. Only the undecided line is split, 55.1% Republican and 44.9% Democratic. That is the 2024 two-party Republican share 60.3 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. Same-office misses: 2024 0.2 at 70 percent and 2020 8.4 at 30 percent. They point the same way, so 60 percent of that blend is kept. It is added to the polling term only. It is not a separate weight. Applied to the polling term: 1.60. Public pollsters: 3. Outliers: 0. 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 -9.9

    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+0.00 added whole

    Open seat. No incumbency term. A negative popularity score is not added on top of the office baseline. No overperformance. An open seat, a scandal, or a missing incumbent gets none. 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 +0.30

    Trump endorsed Kurt Alme. The presidential lean here is R−D 19.9, so the endorsement helps 0.30. 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

    60% of the way from each history block toward the polling term

    The office history and the state's partisan lean differ by more than 12 points, so the history blocks move 60% of the way to the poll. Lean, Trump popularity, and favorability are not shrunk.

25. Model input

    Prediction market

    95% win probability

    Kurt Alme 95.2% is a win probability, not a vote share. Republican win probability 95.2 from Polymarket 95.2% 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 12.0. That margin is shrunk 40% toward the pre-market margin 8.6, which leaves 10.6. It enters once, at 5.0%. The polling term is not nudged. Books under $10,000 and primary markets are ignored.

26. Model input

    State bend

    None

    Not applied.

27. Model input

    State environment adjustment

    National only

    No 2022 governor or Senate race, and no state generic ballot. This state uses the national environment only.

28. Model input

    Early vote

    D+0.2

    No party is on the file. Ballots that match a 2024 presidential county sit at R−D 18.8. The 2024 vote in the same counties was R−D 19.9. The early mix is D+1.2 relative to that vote. Fifteen percent is kept, capped at 1, so D+0.2. 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 10.5 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 10.5. 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

    Independent

    28.1 named

    A named independent is ahead of one major party in the ballot tests the two-party file dropped. Weighted like the polling term: recency half-life 16 days, sample n/(n+350), a registered-voter poll at 0.90, an internal at 0.20. Weighted named shares D 17.8, R 42.5, independent 28.1. That share is taken from the party they outpoll, then the lead is closed to the model margin and capped at 8 points above the polled share. The published margin is the lead over the second-place candidate, not a two-party margin with the independent folded into the other major party.

31. Model input

    Weights

    polling 20.7% · generic 8.8% · stateLean 14.1% · trump 9.4% · favorability 8.7% · history 6.3% · candidate 4.7% · national 4.7% · electorate 3.9% · stateEnv 3.1% · turnout 2.3% · demographics 2.3% · finance 1.6% · issues 1.7% · market 4.9% · 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.

32. County-sum margin

    8.1

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

33. 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.

34. 80% interval

    -0.5 to 16.6

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

35. 95% interval

    -4.9 to 21.1

    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.