2026 U.S. Midterm AI Forecasting Race List — v1.0
Here is a proposed fixed race set for the AI-only comparison: all 35 Senate contests and a stratified sample of 50 House districts (10 from each of five competitiveness tiers). The ratings are used only to create a varied House sample; they are not the experiment’s forecasts. The list does not select candidates or predict winners.
Importable JSON (one record per race):
{
"title": "2026 U.S. Midterm AI Forecasting Race List",
"version": "1.0",
"election_date": "2026-11-03",
"snapshot_date": "2026-10-16",
"race_counts": {
"senate": 35,
"house_sample": 50,
"total": 85
},
"house_sampling": {
"design": "stratified exploratory sample; 10 districts from each of five Cook rating tiers",
"ratings_source": "Cook Political Report ratings reproduced by 270toWin; page marked as of 2026-10-16 (map updated 2026-10-19)",
"seed": "2026-10-20|hf-midterms-v1",
"selection_rule": "Within each tier, sort the source-listed district IDs by ascending unsigned 32-bit FNV-1a hash of the UTF-8 string '<seed>|<district_id>'; select the first 10. District IDs use unpadded numbers (for example, IN-1).",
"tiers": {
"likely_democratic": 10,
"lean_democratic": 10,
"toss_up": 10,
"lean_republican": 10,
"likely_republican": 10
}
},
"sources": [
{
"name": "USPS Postal Bulletin 22694 — Key Elections",
"url": "https://about.usps.com/postal-bulletin/2026/pb22694/html/cover_004.htm"
},
{
"name": "USAGov — Midterm elections",
"url": "https://www.app.cloud.gov/midterm-elections"
},
{
"name": "270toWin — Cook Political Report 2026 House Ratings",
"url": "https://www.270towin.com/2026-house-election/table/cook-political-report-2026-house-ratings/"
}
],
"schema": {
"race_id": "unique identifier",
"office": "U.S. Senate or U.S. House",
"state": "two-letter state code",
"district": "null for Senate; district code for House (AL denotes at-large)",
"selection_stratum": "inclusion rule or rating tier; ratings are selection strata, not this experiment's forecasts"
},
"races": [
{
"race_id": "AL-SEN-2026",
"office": "U.S. Senate",
"state": "AL",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "AK-SEN-2026",
"office": "U.S. Senate",
"state": "AK",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "AR-SEN-2026",
"office": "U.S. Senate",
"state": "AR",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "CO-SEN-2026",
"office": "U.S. Senate",
"state": "CO",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "DE-SEN-2026",
"office": "U.S. Senate",
"state": "DE",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "FL-SEN-2026",
"office": "U.S. Senate",
"state": "FL",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "GA-SEN-2026",
"office": "U.S. Senate",
"state": "GA",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "ID-SEN-2026",
"office": "U.S. Senate",
"state": "ID",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "IL-SEN-2026",
"office": "U.S. Senate",
"state": "IL",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "IA-SEN-2026",
"office": "U.S. Senate",
"state": "IA",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "KS-SEN-2026",
"office": "U.S. Senate",
"state": "KS",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "KY-SEN-2026",
"office": "U.S. Senate",
"state": "KY",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "LA-SEN-2026",
"office": "U.S. Senate",
"state": "LA",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "ME-SEN-2026",
"office": "U.S. Senate",
"state": "ME",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "MA-SEN-2026",
"office": "U.S. Senate",
"state": "MA",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "MI-SEN-2026",
"office": "U.S. Senate",
"state": "MI",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "MN-SEN-2026",
"office": "U.S. Senate",
"state": "MN",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "MS-SEN-2026",
"office": "U.S. Senate",
"state": "MS",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "MT-SEN-2026",
"office": "U.S. Senate",
"state": "MT",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "NE-SEN-2026",
"office": "U.S. Senate",
"state": "NE",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "NH-SEN-2026",
"office": "U.S. Senate",
"state": "NH",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "NJ-SEN-2026",
"office": "U.S. Senate",
"state": "NJ",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "NM-SEN-2026",
"office": "U.S. Senate",
"state": "NM",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "NC-SEN-2026",
"office": "U.S. Senate",
"state": "NC",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "OH-SEN-2026",
"office": "U.S. Senate",
"state": "OH",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "OK-SEN-2026",
"office": "U.S. Senate",
"state": "OK",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "OR-SEN-2026",
"office": "U.S. Senate",
"state": "OR",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "RI-SEN-2026",
"office": "U.S. Senate",
"state": "RI",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "SC-SEN-2026",
"office": "U.S. Senate",
"state": "SC",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "SD-SEN-2026",
"office": "U.S. Senate",
"state": "SD",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "TN-SEN-2026",
"office": "U.S. Senate",
"state": "TN",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "TX-SEN-2026",
"office": "U.S. Senate",
"state": "TX",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "VA-SEN-2026",
"office": "U.S. Senate",
"state": "VA",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "WV-SEN-2026",
"office": "U.S. Senate",
"state": "WV",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "WY-SEN-2026",
"office": "U.S. Senate",
"state": "WY",
"district": null,
"selection_stratum": "all_2026_senate_contests"
},
{
"race_id": "NE-2-HOUSE-2026",
"office": "U.S. House",
"state": "NE",
"district": "2",
"selection_stratum": "likely_democratic"
},
{
"race_id": "OH-13-HOUSE-2026",
"office": "U.S. House",
"state": "OH",
"district": "13",
"selection_stratum": "likely_democratic"
},
{
"race_id": "NV-4-HOUSE-2026",
"office": "U.S. House",
"state": "NV",
"district": "4",
"selection_stratum": "likely_democratic"
},
{
"race_id": "NV-1-HOUSE-2026",
"office": "U.S. House",
"state": "NV",
"district": "1",
"selection_stratum": "likely_democratic"
},
{
"race_id": "NV-3-HOUSE-2026",
"office": "U.S. House",
"state": "NV",
"district": "3",
"selection_stratum": "likely_democratic"
},
{
"race_id": "IN-1-HOUSE-2026",
"office": "U.S. House",
"state": "IN",
"district": "1",
"selection_stratum": "likely_democratic"
},
{
"race_id": "NJ-9-HOUSE-2026",
"office": "U.S. House",
"state": "NJ",
"district": "9",
"selection_stratum": "likely_democratic"
},
{
"race_id": "VA-7-HOUSE-2026",
"office": "U.S. House",
"state": "VA",
"district": "7",
"selection_stratum": "likely_democratic"
},
{
"race_id": "NH-1-HOUSE-2026",
"office": "U.S. House",
"state": "NH",
"district": "1",
"selection_stratum": "likely_democratic"
},
{
"race_id": "MN-2-HOUSE-2026",
"office": "U.S. House",
"state": "MN",
"district": "2",
"selection_stratum": "likely_democratic"
},
{
"race_id": "IA-3-HOUSE-2026",
"office": "U.S. House",
"state": "IA",
"district": "3",
"selection_stratum": "lean_democratic"
},
{
"race_id": "IA-1-HOUSE-2026",
"office": "U.S. House",
"state": "IA",
"district": "1",
"selection_stratum": "lean_democratic"
},
{
"race_id": "NM-2-HOUSE-2026",
"office": "U.S. House",
"state": "NM",
"district": "2",
"selection_stratum": "lean_democratic"
},
{
"race_id": "FL-25-HOUSE-2026",
"office": "U.S. House",
"state": "FL",
"district": "25",
"selection_stratum": "lean_democratic"
},
{
"race_id": "CA-13-HOUSE-2026",
"office": "U.S. House",
"state": "CA",
"district": "13",
"selection_stratum": "lean_democratic"
},
{
"race_id": "TX-28-HOUSE-2026",
"office": "U.S. House",
"state": "TX",
"district": "28",
"selection_stratum": "lean_democratic"
},
{
"race_id": "PA-7-HOUSE-2026",
"office": "U.S. House",
"state": "PA",
"district": "7",
"selection_stratum": "lean_democratic"
},
{
"race_id": "NJ-7-HOUSE-2026",
"office": "U.S. House",
"state": "NJ",
"district": "7",
"selection_stratum": "lean_democratic"
},
{
"race_id": "AZ-1-HOUSE-2026",
"office": "U.S. House",
"state": "AZ",
"district": "1",
"selection_stratum": "lean_democratic"
},
{
"race_id": "PA-10-HOUSE-2026",
"office": "U.S. House",
"state": "PA",
"district": "10",
"selection_stratum": "lean_democratic"
},
{
"race_id": "NC-11-HOUSE-2026",
"office": "U.S. House",
"state": "NC",
"district": "11",
"selection_stratum": "toss_up"
},
{
"race_id": "IA-2-HOUSE-2026",
"office": "U.S. House",
"state": "IA",
"district": "2",
"selection_stratum": "toss_up"
},
{
"race_id": "FL-22-HOUSE-2026",
"office": "U.S. House",
"state": "FL",
"district": "22",
"selection_stratum": "toss_up"
},
{
"race_id": "MT-1-HOUSE-2026",
"office": "U.S. House",
"state": "MT",
"district": "1",
"selection_stratum": "toss_up"
},
{
"race_id": "FL-14-HOUSE-2026",
"office": "U.S. House",
"state": "FL",
"district": "14",
"selection_stratum": "toss_up"
},
{
"race_id": "NC-1-HOUSE-2026",
"office": "U.S. House",
"state": "NC",
"district": "1",
"selection_stratum": "toss_up"
},
{
"race_id": "PA-8-HOUSE-2026",
"office": "U.S. House",
"state": "PA",
"district": "8",
"selection_stratum": "toss_up"
},
{
"race_id": "MI-10-HOUSE-2026",
"office": "U.S. House",
"state": "MI",
"district": "10",
"selection_stratum": "toss_up"
},
{
"race_id": "CO-8-HOUSE-2026",
"office": "U.S. House",
"state": "CO",
"district": "8",
"selection_stratum": "toss_up"
},
{
"race_id": "VA-2-HOUSE-2026",
"office": "U.S. House",
"state": "VA",
"district": "2",
"selection_stratum": "toss_up"
},
{
"race_id": "OH-15-HOUSE-2026",
"office": "U.S. House",
"state": "OH",
"district": "15",
"selection_stratum": "lean_republican"
},
{
"race_id": "OH-10-HOUSE-2026",
"office": "U.S. House",
"state": "OH",
"district": "10",
"selection_stratum": "lean_republican"
},
{
"race_id": "FL-27-HOUSE-2026",
"office": "U.S. House",
"state": "FL",
"district": "27",
"selection_stratum": "lean_republican"
},
{
"race_id": "FL-13-HOUSE-2026",
"office": "U.S. House",
"state": "FL",
"district": "13",
"selection_stratum": "lean_republican"
},
{
"race_id": "KY-6-HOUSE-2026",
"office": "U.S. House",
"state": "KY",
"district": "6",
"selection_stratum": "lean_republican"
},
{
"race_id": "PA-1-HOUSE-2026",
"office": "U.S. House",
"state": "PA",
"district": "1",
"selection_stratum": "lean_republican"
},
{
"race_id": "CO-5-HOUSE-2026",
"office": "U.S. House",
"state": "CO",
"district": "5",
"selection_stratum": "lean_republican"
},
{
"race_id": "ME-2-HOUSE-2026",
"office": "U.S. House",
"state": "ME",
"district": "2",
"selection_stratum": "lean_republican"
},
{
"race_id": "NY-21-HOUSE-2026",
"office": "U.S. House",
"state": "NY",
"district": "21",
"selection_stratum": "lean_republican"
},
{
"race_id": "MN-1-HOUSE-2026",
"office": "U.S. House",
"state": "MN",
"district": "1",
"selection_stratum": "lean_republican"
},
{
"race_id": "AK-AL-HOUSE-2026",
"office": "U.S. House",
"state": "AK",
"district": "AL",
"selection_stratum": "likely_republican"
},
{
"race_id": "KS-2-HOUSE-2026",
"office": "U.S. House",
"state": "KS",
"district": "2",
"selection_stratum": "likely_republican"
},
{
"race_id": "NE-1-HOUSE-2026",
"office": "U.S. House",
"state": "NE",
"district": "1",
"selection_stratum": "likely_republican"
},
{
"race_id": "TX-9-HOUSE-2026",
"office": "U.S. House",
"state": "TX",
"district": "9",
"selection_stratum": "likely_republican"
},
{
"race_id": "FL-16-HOUSE-2026",
"office": "U.S. House",
"state": "FL",
"district": "16",
"selection_stratum": "likely_republican"
},
{
"race_id": "MO-2-HOUSE-2026",
"office": "U.S. House",
"state": "MO",
"district": "2",
"selection_stratum": "likely_republican"
},
{
"race_id": "TX-23-HOUSE-2026",
"office": "U.S. House",
"state": "TX",
"district": "23",
"selection_stratum": "likely_republican"
},
{
"race_id": "FL-9-HOUSE-2026",
"office": "U.S. House",
"state": "FL",
"district": "9",
"selection_stratum": "likely_republican"
},
{
"race_id": "FL-7-HOUSE-2026",
"office": "U.S. House",
"state": "FL",
"district": "7",
"selection_stratum": "likely_republican"
},
{
"race_id": "NV-2-HOUSE-2026",
"office": "U.S. House",
"state": "NV",
"district": "2",
"selection_stratum": "likely_republican"
}
]
}
The House sample is exploratory rather than statistically representative of all 435 districts. The dated ratings snapshot and deterministic seed are recorded in the JSON so the selection can be audited. If the group agrees on a different set, we can publish a versioned revision before forecasts are collected. No race should be added or removed after forecasts begin without documenting that change.