The Republican nominee wins the Iowa US Senate race in 2026.
Iowa holds a US Senate election in November 2026. This resolves as true if the official Republican nominee wins the general election or any subsequent runoff.
Across 6 frontier models answering independently, the panel treats this as close to settled: the median is 86%.
They broadly agree, 16 points between DeepSeek at 92% and Claude at 76%.
Money disagrees. The market sits at 55%, so the models are 31 points more confident than people with cash on the outcome — one of the wider gaps in the archive.
Nothing is settled until 4 Nov 2026, when the outcome is checked against sources and every number above gets a permanent score.
- AI edge
- +31 pts
- Moved this week
- -3 pts
- Volume
- $667K
The models are sharply more confident than traders risking real money: 86% against 55%.
What each one said
-
DeepSeekDeepSeek
Iowa is a red-leaning state and Ernst's retirement opened a race Republicans are favored to hold.
- Iowa voted Trump by ~8 points in 2024 and has not elected a Democratic senator since 2014, giving the GOP a strong structural edge.
- GOP nominee Ashley Hinson faces Democrat Josh Riley; polling has shown a competitive but Republican-tilted race in a state Trump carried twice.
- The main risk is a national Democratic wave or a scandal-driven collapse, but with only days left and no such shock, the GOP remains clearly favored.
92% -
GPTOpenAI
Iowa’s strong Republican federal baseline makes an upset depend on a major late polling or turnout surprise.
- The GOP nominee needs only win the November 3 general election; Iowa has no Senate runoff system.
- Republicans carried Iowa’s 2024 Senate race by roughly 20 points and hold both Senate seats, a far stronger baseline than a toss-up state.
- A credible final-week poll showing the Democrat within low single digits, or a major GOP nominee scandal, would sharply cut this estimate.
91% -
QwenAlibaba
Iowa's R+8 partisan lean makes this nearly a lock unless a historic national wave hits.
- Iowa voted R+9 in 2024 and both House seats are Republican; no Democrat has won a statewide Iowa race since 2012.
- Even in strong Democratic national environments (2018, 2020), Republicans held Iowa Senate seats comfortably.
- A Democratic win would require either a national blue wave exceeding 2006 magnitude or a catastrophic Republican candidate scandal.
89% -
GeminiGoogle
Iowa's strong Republican shift and incumbent advantages make the state a heavy lift for Democrats even in midterms.
- Incumbent Joni Ernst or a successor benefits from Iowa voting roughly 8-10 points to the right of the national popular vote.
- Midterm dynamics under a likely national environment rarely overcome high baseline partisan lean without flawed candidates.
- A competitive Democratic challenge would require a massive suburban shift and rural stabilization that hasn't materialized since 2018.
82% -
GrokxAI
Incumbent Joni Ernst holds a red-state seat four days from Election Day.
- Ernst is the GOP nominee; Iowa last flipped Senate in 2014 and has voted R by 8+ pts in recent cycles.
- Democrats must clear a 6-8 pt polling deficit with no runoff mechanism and only 4 days left.
- A late scandal or 8-pt polling error would flip it; neither has a 2022-24 Iowa precedent.
82% -
ClaudeAnthropic
Joni Ernst's open seat leans Republican in a red-trending state, but 2026 midterm climate adds some risk.
- Iowa has voted Republican in Senate races consistently since 2014 and Trump won it by ~13 points in 2024.
- Open seat dynamics and a potentially unfavorable midterm environment for the GOP introduce modest downside risk.
- Polling and fundraising through October 2026 would be the key signal; absent strong Democratic momentum, GOP remains clear favorite.
76%
6 of 6 models answered · 16 points between the highest and lowest. None was shown the market price.
Resolution criteria
This market will resolve according to the winner of the 2026 midterm Iowa U.S. Senate election, inclusive of any run-offs. A candidate shall be considered to represent a party in the event that he or she is the nominee of the party in question. Candidates other than the Democratic or Republican nominee (e.g., Greens, Libertarian, independent) may be added at a later date. Candidates who run as independents will not be encompassed by the “Democrat” or “Republican” options regardless of any affiliation they may have with the party. The candidates may be named in the contract for the convenience of traders. In the event that any named candidate is replaced as the nominee of their respective party prior to election day, the name in the contract will be updated and the market will resolve based on the replacement nominee of the party. The resolution source for this market is the Associated Press, Fox News, and NBC. This market will resolve once all three sources call the race for the same candidate. If all three sources haven’t called the race in this state for the same candidate, this market will resolve based on the official certification.
Question sourced from Polymarket on 31 Oct 2026. Forecast by google/gemini-3.8-flash, anthropic/claude-sonnet-5, openai/gpt-5.6-terra, x-ai/grok-4.6, deepseek/deepseek-v4.1-flash, qwen/qwen3.8-max-0902 via OpenRouter.