COYNTOSS / BETA 0.1 2026 SENATE

October 22 frozen research reference; current refresh blocked

October 22, 2026 is the latest verified reference

The latest refresh attempt (October 24, 2026) did not qualify: candidate matchups failed validation; poll timing failed validation; poll publication timestamps are missing for 338 of 368 records; the source feed is stale; the feed publication timestamp is stale or inconsistent. Maine's frozen race is Troy Jackson vs Susan Collins; archived feed rows for the former Platner matchup remain candidate-mismatched and are not promoted into a current refresh. This page retains the October 22, 2026 research reference and does not make a current forecast claim.

THE 2026 SENATE · OCTOBER 22, 2026

A tighter poll blend, held to the record.

COYNTOSS Beta 0.1 tests a prespecified change to how polls influence the Senate forecast. It is a public research release alongside the stable model, with the full race-level record below.

Frozen as of October 22, 2026·Built 2026-10-24T19:23:17Z

THE CHAMBER

Chance of a Democratic-caucus majority

61.9%Democratic caucus favored
D caucus61.9%R38.1%

400000 simulation draws · 20261023 seed · threshold 51 seats

EXPECTED SEATS

Where the average lands

Democratic caucus51.1
Republican48.9

Middle 80% of outcomes 48–54 Democratic-caucus seats · median 51

Expected seat counts include incumbents and allied independents according to the source caucus assignment.

Model COYNTOSS Beta 0.1 (D)Forecast date October 22, 2026Source state October 22 frozen research reference; current refresh blocked

ALL 35 CONTESTS · OCTOBER 22, 2026

The race-by-race forecast

Margins name the candidate ahead; each win probability appears beside the candidate it describes. Senate caucus effects are reported separately from party identity.

Frozen research reference
COYNTOSS Beta 0.1

2026 U.S. Senate race forecasts for all 35 races
StateCandidatesProjected marginWin probabilityRatingPollingModel comparisons
AlabamaSouth Everett Wess (D)Barry Moore (R) Moore (R) +22.6
Wess (D) 0.4%Moore (R) 99.6%
SafeSafe R 2polls · latest fieldwork October 16, 2026 Moore (R) +0.1 margin · Moore (R) +0.0 ppvs same-input APublished stable: Moore (R) +22.5 · Wess (D) 0.4%Beta change: Moore (R) +0.1 margin · Moore (R) +0.0 pp
AlaskaWest Mary Peltola (D)Dan Sullivan (R) Peltola (D) +1.2
Peltola (D) 63.0%Sullivan (R) 37.0%
Toss-upToss-up 24polls · latest fieldwork October 16, 2026 Sullivan (R) +0.7 margin · Sullivan (R) +6.4 ppvs same-input APublished stable: Peltola (D) +1.9 · Peltola (D) 69.3%Beta change: Sullivan (R) +0.7 margin · Sullivan (R) +6.3 pp
ArkansasSouth Hallie Shoffner (D)Tom Cotton (R) Cotton (R) +17.3
Shoffner (D) 0.2%Cotton (R) 99.8%
SafeSafe R 7polls · latest fieldwork October 13, 2026 Cotton (R) +1.8 margin · Cotton (R) +0.1 ppvs same-input APublished stable: Cotton (R) +15.5 · Shoffner (D) 0.3%Beta change: Cotton (R) +1.8 margin · Cotton (R) +0.2 pp
ColoradoWest John Hickenlooper (D)Mark Baisley (R) Hickenlooper (D) +20.6
Hickenlooper (D) 96.2%Baisley (R) 3.8%
SafeSafe D 0polls · latest fieldwork not available No change margin · No changevs same-input APublished stable: Hickenlooper (D) +20.6 · Hickenlooper (D) 96.2%Beta change: No change margin · Baisley (R) +0.1 pp
DelawareSouth Chris Coons (D)Michael Katz (R) Coons (D) +24.4
Coons (D) 97.9%Katz (R) 2.1%
SafeSafe D 0polls · latest fieldwork not available No change margin · No changevs same-input APublished stable: Coons (D) +24.4 · Coons (D) 98.0%Beta change: No change margin · Katz (R) +0.1 pp
FloridaSouth Angie Nixon (D)Ashley Moody (R) Moody (R) +5.7
Nixon (D) 7.3%Moody (R) 92.7%
LeanLean R 16polls · latest fieldwork October 20, 2026 Nixon (D) +0.6 margin · Nixon (D) +1.6 ppvs same-input APublished stable: Moody (R) +6.2 · Nixon (D) 5.8%Beta change: Nixon (D) +0.6 margin · Nixon (D) +1.5 pp
GeorgiaSouth Jon Ossoff (D)Mike Collins (R) Ossoff (D) +7.8
Ossoff (D) 97.3%Collins (R) 2.7%
LikelyLikely D 16polls · latest fieldwork October 20, 2026 Collins (R) +0.2 margin · Collins (R) +0.2 ppvs same-input APublished stable: Ossoff (D) +8.0 · Ossoff (D) 97.5%Beta change: Collins (R) +0.2 margin · Collins (R) +0.3 pp
IdahoWest Todd Achilles (I)Jim Risch (R)Todd Achilles win counts toward Democratic caucus Risch (R) +30.1
Achilles (I) 0.9%Risch (R) 99.1%
SafeSafe R 0polls · latest fieldwork not available No change margin · No changevs same-input APublished stable: Risch (R) +30.1 · Achilles (I) 0.9%Beta change: No change margin · Achilles (I) +0.1 pp
IllinoisMidwest Juliana Stratton (D)Don Tracy (R) Stratton (D) +19.2
Stratton (D) 98.6%Tracy (R) 1.4%
SafeSafe D 1polls · latest fieldwork October 20, 2026 Stratton (D) +0.2 margin · Stratton (D) +0.0 ppvs same-input APublished stable: Stratton (D) +19.0 · Stratton (D) 98.5%Beta change: Stratton (D) +0.2 margin · Stratton (D) +0.1 pp
IowaMidwest Josh Turek (D)Ashley Hinson (R) Hinson (R) +1.5
Turek (D) 33.8%Hinson (R) 66.2%
Toss-upToss-up 30polls · latest fieldwork October 19, 2026 Hinson (R) +0.9 margin · Hinson (R) +9.5 ppvs same-input APublished stable: Hinson (R) +0.6 · Turek (D) 43.7%Beta change: Hinson (R) +0.9 margin · Hinson (R) +9.9 pp
KansasMidwest Adam Hamilton (D)Roger Marshall (R) Marshall (R) +4.8
Hamilton (D) 15.1%Marshall (R) 84.9%
LeanLean R 11polls · latest fieldwork October 14, 2026 Marshall (R) +1.5 margin · Marshall (R) +8.5 ppvs same-input APublished stable: Marshall (R) +3.3 · Hamilton (D) 23.6%Beta change: Marshall (R) +1.5 margin · Marshall (R) +8.6 pp
KentuckySouth Charles Booker (D)Andy Barr (R) Barr (R) +19.6
Booker (D) 2.2%Barr (R) 97.8%
SafeSafe R 1polls · latest fieldwork August 27, 2026 Barr (R) +0.4 margin · Barr (R) +0.2 ppvs same-input APublished stable: Barr (R) +19.2 · Booker (D) 2.3%Beta change: Barr (R) +0.4 margin · Barr (R) +0.0 pp
LouisianaSouth Jamie Davis (D)Julia Letlow (R) Letlow (R) +12.7
Davis (D) 7.1%Letlow (R) 92.9%
LikelyLikely R 1polls · latest fieldwork September 19, 2026 Letlow (R) +0.5 margin · Letlow (R) +0.7 ppvs same-input APublished stable: Letlow (R) +12.2 · Davis (D) 7.8%Beta change: Letlow (R) +0.5 margin · Letlow (R) +0.8 pp
MaineNortheast Troy Jackson (D)Susan Collins (R) Jackson (D) +2.5
Jackson (D) 75.1%Collins (R) 24.9%
Toss-upToss-up 26polls · latest fieldwork October 14, 2026 Jackson (D) +0.7 margin · Jackson (D) +5.9 ppvs same-input APublished stable: Jackson (D) +1.9 · Jackson (D) 69.3%Beta change: Jackson (D) +0.7 margin · Jackson (D) +5.9 pp
MassachusettsNortheast Ed Markey (D)John Deaton (R) Markey (D) +33.5
Markey (D) 100.0%Deaton (R) 0.0%
SafeSafe D 6polls · latest fieldwork October 18, 2026 Markey (D) +0.9 margin · Markey (D) +0.0 ppvs same-input APublished stable: Markey (D) +32.6 · Markey (D) 100.0%Beta change: Markey (D) +0.9 margin · Deaton (R) +0.0 pp
MichiganMidwest Abdul El-Sayed (D)Mike Rogers (R) El-Sayed (D) +4.3
El-Sayed (D) 87.0%Rogers (R) 13.0%
LeanLean D 34polls · latest fieldwork October 18, 2026 El-Sayed (D) +0.5 margin · El-Sayed (D) +3.0 ppvs same-input APublished stable: El-Sayed (D) +3.7 · El-Sayed (D) 84.1%Beta change: El-Sayed (D) +0.5 margin · El-Sayed (D) +2.8 pp
MinnesotaMidwest Peggy Flanagan (D)Michele Tafoya (R) Flanagan (D) +7.0
Flanagan (D) 96.0%Tafoya (R) 4.0%
LeanLean D 13polls · latest fieldwork October 12, 2026 Flanagan (D) +1.2 margin · Flanagan (D) +2.9 ppvs same-input APublished stable: Flanagan (D) +5.8 · Flanagan (D) 93.0%Beta change: Flanagan (D) +1.2 margin · Flanagan (D) +3.0 pp
MississippiSouth Scott Colom (D)Cindy Hyde-Smith (R) Hyde-Smith (R) +16.6
Colom (D) 6.9%Hyde-Smith (R) 93.1%
SafeSafe R 0polls · latest fieldwork not available No change margin · No changevs same-input APublished stable: Hyde-Smith (R) +16.6 · Colom (D) 7.0%Beta change: No change margin · Hyde-Smith (R) +0.1 pp
MontanaWest Seth Bodnar (I)Kurt Alme (R)Seth Bodnar win counts toward Democratic caucus Alme (R) +15.3
Bodnar (I) 2.3%Alme (R) 97.7%
SafeSafe R 2polls · latest fieldwork September 17, 2026 Bodnar (I) +0.6 margin · Bodnar (I) +0.3 ppvs same-input APublished stable: Alme (R) +15.8 · Bodnar (I) 2.0%Beta change: Bodnar (I) +0.6 margin · Bodnar (I) +0.3 pp
NebraskaMidwest Dan Osborn (I)Pete Ricketts (R)Dan Osborn win counts toward Democratic caucus Ricketts (R) +5.0
Osborn (I) 13.9%Ricketts (R) 86.1%
LeanLean R 9polls · latest fieldwork October 3, 2026 Ricketts (R) +0.6 margin · Ricketts (R) +2.9 ppvs same-input APublished stable: Ricketts (R) +4.4 · Osborn (I) 16.8%Beta change: Ricketts (R) +0.6 margin · Ricketts (R) +2.9 pp
New HampshireNortheast Chris Pappas (D)John Sununu (R) Pappas (D) +7.8
Pappas (D) 97.4%Sununu (R) 2.6%
LikelyLikely D 19polls · latest fieldwork October 20, 2026 Pappas (D) +0.6 margin · Pappas (D) +0.9 ppvs same-input APublished stable: Pappas (D) +7.2 · Pappas (D) 96.5%Beta change: Pappas (D) +0.6 margin · Pappas (D) +0.9 pp
New JerseyNortheast Cory Booker (D)Justin Murphy (R) Booker (D) +17.3
Booker (D) 93.8%Murphy (R) 6.2%
SafeSafe D 0polls · latest fieldwork not available No change margin · No changevs same-input APublished stable: Booker (D) +17.3 · Booker (D) 94.0%Beta change: No change margin · Murphy (R) +0.2 pp
New MexicoWest Ben Ray Luján (D)Larry Marker (R) Luján (D) +16.3
Luján (D) 99.3%Marker (R) 0.7%
SafeSafe D 3polls · latest fieldwork October 9, 2026 Marker (R) +0.3 margin · Marker (R) +0.1 ppvs same-input APublished stable: Luján (D) +16.6 · Luján (D) 99.4%Beta change: Marker (R) +0.3 margin · Marker (R) +0.1 pp
North CarolinaSouth Roy Cooper (D)Michael Whatley (R) Cooper (D) +8.1
Cooper (D) 97.7%Whatley (R) 2.3%
LikelyLikely D 26polls · latest fieldwork October 20, 2026 Whatley (R) +1.0 margin · Whatley (R) +0.9 ppvs same-input APublished stable: Cooper (D) +9.1 · Cooper (D) 98.5%Beta change: Whatley (R) +1.0 margin · Whatley (R) +0.8 pp
OhioMidwest Sherrod Brown (D)Jon Husted (R) Brown (D) +1.8
Brown (D) 68.2%Husted (R) 31.8%
Toss-upToss-up 26polls · latest fieldwork October 19, 2026 Husted (R) +0.7 margin · Husted (R) +6.4 ppvs same-input APublished stable: Brown (D) +2.5 · Brown (D) 74.9%Beta change: Husted (R) +0.7 margin · Husted (R) +6.7 pp
OklahomaSouth N'Kiyla Thomas (D)Kevin Hern (R) Hern (R) +28.0
Thomas (D) 1.3%Hern (R) 98.7%
SafeSafe R 0polls · latest fieldwork not available No change margin · No changevs same-input APublished stable: Hern (R) +28.0 · Thomas (D) 1.3%Beta change: No change margin · Hern (R) +0.0 pp
OregonWest Jeff Merkley (D)David Brock Smith (R) Merkley (D) +25.5
Merkley (D) 98.2%Smith (R) 1.8%
SafeSafe D 0polls · latest fieldwork not available No change margin · No changevs same-input APublished stable: Merkley (D) +25.5 · Merkley (D) 98.1%Beta change: No change margin · Merkley (D) +0.1 pp
Rhode IslandNortheast Jack Reed (D)Raymond Mackay (R) Reed (D) +29.0
Reed (D) 100.0%Mackay (R) 0.0%
SafeSafe D 5polls · latest fieldwork October 11, 2026 Mackay (R) +0.3 margin · Mackay (R) +0.0 ppvs same-input APublished stable: Reed (D) +29.3 · Reed (D) 100.0%Beta change: Mackay (R) +0.3 margin · Reed (D) +0.0 pp
South CarolinaSouth Annie Andrews (D)Darline Graham Nordone (R) Nordone (R) +6.2
Andrews (D) 9.2%Nordone (R) 90.8%
LeanLean R 8polls · latest fieldwork October 18, 2026 Nordone (R) +0.9 margin · Nordone (R) +3.2 ppvs same-input APublished stable: Nordone (R) +5.4 · Andrews (D) 12.3%Beta change: Nordone (R) +0.9 margin · Nordone (R) +3.1 pp
South DakotaMidwest Brian Bengs (I)Mike Rounds (R)Brian Bengs win counts toward Democratic caucus Rounds (R) +17.9
Bengs (I) 0.1%Rounds (R) 99.9%
SafeSafe R 8polls · latest fieldwork October 20, 2026 Rounds (R) +1.7 margin · Rounds (R) +0.1 ppvs same-input APublished stable: Rounds (R) +16.2 · Bengs (I) 0.2%Beta change: Rounds (R) +1.7 margin · Rounds (R) +0.1 pp
TennesseeSouth Marquita Bradshaw (D)Bill Hagerty (R) Hagerty (R) +26.6
Bradshaw (D) 0.5%Hagerty (R) 99.5%
SafeSafe R 1polls · latest fieldwork August 26, 2026 Bradshaw (D) +0.0 margin · Bradshaw (D) +0.0 ppvs same-input APublished stable: Hagerty (R) +26.6 · Bradshaw (D) 0.5%Beta change: Bradshaw (D) +0.0 margin · Bradshaw (D) +0.1 pp
TexasSouth James Talarico (D)Ken Paxton (R) Even
Talarico (D) 49.6%Paxton (R) 50.4%
Toss-upToss-up 43polls · latest fieldwork October 19, 2026 Paxton (R) +1.3 margin · Paxton (R) +13.4 ppvs same-input APublished stable: Talarico (D) +1.2 · Talarico (D) 63.3%Beta change: Paxton (R) +1.3 margin · Paxton (R) +13.7 pp
VirginiaSouth Mark Warner (D)Bert Mizusawa (R) Warner (D) +16.2
Warner (D) 92.7%Mizusawa (R) 7.3%
SafeSafe D 0polls · latest fieldwork not available No change margin · No changevs same-input APublished stable: Warner (D) +16.2 · Warner (D) 92.8%Beta change: No change margin · Mizusawa (R) +0.2 pp
West VirginiaSouth Rachel Fetty Anderson (D)Shelley Moore Capito (R) Capito (R) +39.1
Anderson (D) 0.2%Capito (R) 99.8%
SafeSafe R 0polls · latest fieldwork not available No change margin · No changevs same-input APublished stable: Capito (R) +39.1 · Anderson (D) 0.3%Beta change: No change margin · Capito (R) +0.0 pp
WyomingWest James Byrd (D)Harriet Hageman (R) Hageman (R) +40.0
Byrd (D) 0.2%Hageman (R) 99.8%
SafeSafe R 0polls · latest fieldwork not available No change margin · No changevs same-input APublished stable: Hageman (R) +40.0 · Byrd (D) 0.2%Beta change: No change margin · Byrd (D) +0.0 pp

“Change vs same-input A” compares Beta with the production-equivalent Model A on the shared frozen input. “Published stable” uses the actual stable snapshot October 22, 2026 and its 50000-draw simulation. Positive margin changes favor the named candidate. Candidate party identity and Senate caucus effect are shown separately, including independent candidates.

PUBLISHED STABLE · SAME-INPUT A · BETA

Three estimates, two comparisons.

The published stable snapshot is shown with its actual release and simulation dates. Model A and Beta use the same frozen input vintage and common simulation settings, isolating the model specification change.

Stable-versus-Beta differences include a model change and Monte Carlo sampling differences. Both forecasts use the October 22 source vintage. Stable: 50000 draws (RETRO-20261022-R03); Beta: 400000 draws (20261023 seed).

Production-equivalent Model A on the same frozen input is a production-equivalent research benchmark, not the published stable forecast. Model D reduces Model A’s polling influence to 80% of its original level, pulling the estimate toward fundamentals when polls differ from them. This is a specification explanation, not a claim about current conditions.

CHAMBER CONTROL · DEMOCRATIC CAUCUSPublished release dates shown below
Published stable68.6%forecast October 22, 2026
simulation October 22, 2026 · 50000 draws
Model A · same input68.4%forecast October 22, 2026
simulation 400000 draws · seed 20261023
Beta 0.161.9%forecast October 22, 2026
simulation 400000 draws · seed 20261023

Beta vs published stable−6.7 percentage pointsIncludes model change and Monte Carlo sampling differences.

Beta vs same-input A−6.5 percentage pointsModel comparison on the shared frozen input.

Expected D-caucus seats · stable
51.5
Expected D-caucus seats · A
51.5
Expected D-caucus seats · Beta
51.1
Beta seat change vs stable
-0.39 seats
Beta seat change vs A
-0.38 seats
Stable model
v0.53.1 · 2026-10-22-01
Stable feed published
2026-10-23T03:31:19Z
Stable simulation run
RETRO-20261022-R03 · 2026-10-23T05:23:42Z
Beta model specification
4aa26a9a6b2596e2…
Stable capture checked
2026-10-24T19:10:45.171161+00:00

HOW IT WORKS

A prespecified model change

Research lineage
v10–v22

01

What changes

Beta 0.1 uses candidate model D. The model specification is versioned and identified by a SHA-256 digest so later research can preserve this release as a fixed benchmark.

The Model A polling center is retained while polling influence is reduced: α_D = 0.80 × α_A and M_D = (1 − α_D)F + α_D P_A + Q. Candidate adjustment Q and Model A uncertainty remain unchanged.

02

Why test it

Prior COYNTOSS research tested polling aggregation and polling influence across multiple election cycles. Historical backtests are evidence for testing a change, not proof it will improve future forecasts.

No parameter was tuned to the 2026 results. The 2026 snapshot predates Election Day and is not outcome validation.

03

Limits of this release

The source status is October 22 frozen research reference; current refresh blocked. This page shows the October 22, 2026 reference; the attempted refresh did not qualify as a forecast update.

The tournament used historical comparisons with vintage and cohort limitations. Prospective performance remains unknown.

BOUNDED HISTORICAL TOURNAMENT · A–J

One cohort, four scores

142 race-horizon observations · 71 races · 2018, 2020, 2022 and 2024 · D−30 and D−1

Historical A through J model comparison on 142 observations
ModelMargin RMSE ↓Margin MAE ↓Brier ↓Log loss ↓
A4.8683.7150.04100.1429
B4.6283.5210.04240.1420
C4.5953.5630.04300.1478
D Beta 0.14.5973.4600.03560.1261
E4.4023.3420.03610.1252
F4.3533.3830.03700.1310
G4.8483.6680.04090.1428
H4.5603.4140.03550.1258
I4.3723.3010.03610.1251
J4.3183.3380.03700.1308

Lower is better. D beat A on pooled RMSE, Brier and log loss at both horizons, with lower margin RMSE in all four cycles; its pooled RMSE was 4.597 vs 4.868 for A, Brier 0.03562 vs 0.04099, and log loss 0.12613 vs 0.14293. J had the lowest pooled RMSE, I the lowest MAE and log loss, and H the lowest Brier score. D is the simpler polling-only choice for the first prospective baseline, not an all-metric winner. E improved margin scores over D but had a slightly worse Brier score and worse 2024 probability scores; E remains the primary shadow challenger.

The cohort was extensively inspected and is an approximate-vintage retrospective, not a publication-vintage-certified backtest or prospective validation. Repeated D−30 and D−1 rows share each race outcome and are not independent observations. No significance or superiority claim is supported by these four cycles.

Specification and source receipts

Model identity

Model
COYNTOSS Beta 0.1 · coyntoss-beta-0.1-d
Specification SHA-256
4aa26a9a6b2596e2ccd17f6bc7da99b045929a17e3e6e1ee7af6401f37b5bb38
Config version
beta-0.1-selection-2
Generated
2026-10-24T19:23:17Z
Source receipts
16 recorded source receipts
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  • Source receipt 107230e7dddc935414a26c81bcf391e53f3c368ca753e455f974a03eee8673dbb3
  • Source receipt 11d4e3563fe71478f44cf4bb58f9948d45ba17d4484d10e731ec54d15778beb24f
  • Source receipt 121a5015aaee028016fd576ba60dac1221fb07b9a2c3283933d0d192043f1dd2c8
  • Source receipt 1321b0584d4d6d38fe345a65a4ce32d9e51ae79f3c15bf4fc34b7613d536f39657
  • Source receipt 149a4055138acda09d81fa5df4efd08c0f110c568a3d83a65e334e4f1a71df0f17
  • Source receipt 15d17a5718b8a26858b0fcd6408fb728740e49db376f855c4079a6ca78c6c6629a
  • Published stable receipt 147e81abd46f6f57412a49bebc9f533ca47a71c9d0803ae63a4c256f86701267d

RESEARCH HISTORY

Built from a longer record.

Beta 0.1 follows experiments conducted through COYNTOSS v22. The experimental lineage remains distinct from the stable forecast, which was not changed by this work.

v10–v22

Research archive and prior model experiments

Beta 0.1

New fixed benchmark, selected from a bounded A–J tournament

Next

Preserve prospective predictions, score after the election, and release any adopted change as a new version