Prediction Tool

Recent district vote is a separate historical what-if: the latest comparable contested general-election result for the same district and office, from 2024 or otherwise 2022. It uses exact Democratic votes divided by Democratic plus Republican votes, with no weights or swing adjustment. Statewide offices, U.S. Senate, current multi-candidate races, races without a D/R matchup, and races without comparable history stay manual. No registration or polling fallback is used. Historical vote shares are not a 2026 forecast.

For the existing baseline, swing and party-sweep presets, a sole Democratic or Republican candidate against No Party candidates is picked as an explicit assumption. No vote percentage is assigned to that assumption; you can override it. This rule does not apply to Pick the Polls or Recent district vote.

The Auto-fill Scenario baseline uses the September 17–20 Marist poll for governor and U.S. Senate. The separate Pick the Polls control chooses the latest qualifying poll with a verified field date and all current candidates, and displays the source beside the applied pick; these controls can use different surveys. For other races, the baseline uses active voter registrations from the Iowa Secretary of State’s October 1, 2026 reports. House and Senate races use exact district totals; U.S. House races use the county portions inside that congressional district; statewide offices use all 99 counties. Each race shows its source, date, and geography.

For registration-based races, the Democratic baseline is active Democratic registrations divided by active Democratic plus Republican registrations. Poll-based races use the D/R share of poll responses. A Democratic swing adds 5 percentage points to the Democratic share; a Republican swing subtracts 5. The party above 50% gets the suggested pick. A five-point shift in vote share changes the D–R margin by ten points. Identical settings produce identical suggestions, including after a reset or reload.

No-party and other registrations are shown separately and are not assigned to either candidate. Inactive registrations are excluded. Registration is not voting intention: voters can cross party lines, and these scenarios do not estimate turnout or how no-party voters will vote. Poll-based shares exclude other candidates and undecided responses. Unsupported races and exact ties stay blank after Auto-fill. The sole-major-party assumption applies to qualifying No Party matchups as described above. You can always make a manual choice. These are transparent what-if scenarios, not measured 2026 winning probabilities. Party sweeps choose the selected party where it has a candidate. If that party is absent and the race has one other major-party candidate against only No Party candidates, the sole-major-party assumption applies instead. This exception is labeled in the race preview.