Polymarket likes Democrats almost everywhere in Iowa.
Rob Sand is an 87.5-cent favorite for governor. Democrats are favored in three of the state’s four House districts. Put the six major races together and the board expects Democrats to win roughly half of them after Republicans entered 2026 holding all six.
Then there is the Senate race. Democrat Josh Turek is just 41.5 cents against Republican Ashley Hinson, despite recent polling showing everything from a Turek lead to a relatively close Hinson advantage.
That’s what makes Iowa’s board interesting. It isn’t just pricing some ticket splitting. It is pricing a much bigger gap between Sand and Turek than the recent polling has shown.
Iowa Senate race odds
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What changed
Since our Sept. 14 snapshot, Polymarket’s national Senate board has moved noticeably toward Democrats. Democratic control of the chamber went from 52.5 cents to 62.5 cents.
Iowa barely followed.
Turek moved from 39.5 to 41.5 cents over the same stretch. So while the national Senate picture moved about 10 points toward Democrats, one of the races that could matter to control of the chamber moved only two.
The biggest new piece of information was the Marist poll released Sept. 22.
Marist surveyed 1,050 Iowa registered voters from Sept. 17–20 and found Turek ahead of Hinson 50% to 42%. Sand led Lahn 54% to 42%, with independents breaking for Sand 57% to 33%.
The Senate market barely moved.
The split Polymarket is pricing
Ticket splitting in Iowa is clearly possible. The polling already shows it.
But the size of the split is the interesting part.
Marist has Sand ahead by 12 and Turek ahead by eight, a four-point difference between the Democratic candidates.
Emerson’s Sept. 3 poll tells a much more Republican story. Among 750 likely voters, Hinson leads Turek 50% to 45%, while Sand leads Lahn 49% to 46%. Emerson estimates that roughly 6% of voters are supporting both Hinson and Sand.
That’s an eight-point gap between the two races.
So the two pollsters disagree substantially about the overall state of the Senate race. Marist has Turek +8. Emerson has Hinson +5.
But they agree on something important: Sand runs ahead of Turek by somewhere around four to eight points.
Polymarket is pricing a much more dramatic difference.
Sand trades like a strong favorite while Turek trades like a clear underdog. In other words, the board isn’t merely saying some Sand voters will also vote for Hinson. It’s assigning very different levels of confidence to two Democrats running statewide on the same ballot.
Why Hinson can run ahead
There are legitimate reasons the Senate and governor markets don’t have to move together.
Hinson has an established congressional profile and is already known to Iowa voters. Turek has more work to do on name recognition. Emerson’s August polling had Sand at 51% favorable and 31% unfavorable, compared with 42% favorable and 27% unfavorable for Turek.
The polling samples matter too.
Marist surveyed registered voters. Emerson used likely voters. In a midterm election, those can produce meaningfully different electorates. Marist itself reports a ±4.4-point margin of error for its registered-voter sample, while Emerson reports a ±3.6-point credibility interval for its likely-voter sample.
There’s also an interesting difference between how Iowans say they will vote and who they expect to win.
Marist has Turek leading the Senate vote question, but its respondents still expect Hinson to win the race. That helps explain why a prediction market could remain more skeptical of Turek than the headline polling numbers alone would suggest.
The question is how much skepticism belongs in the price.
The Iowa House races
The House markets make the statewide split even more noticeable.
IA-1: Christina Bohannan 82¢ vs. Mariannette Miller-Meeks 17¢. This is the third consecutive general-election matchup between the two. Miller-Meeks is the incumbent, but Polymarket currently gives Bohannan a substantial advantage.
IA-2: Lindsay James 52.5¢ vs. Joe Mitchell 45¢. This is Hinson’s open House seat. Hinson is leaving the district to run for Senate, and Polymarket has the race essentially around even, with James holding a small edge. Iowa’s certified primary results confirm James and Mitchell as the two major-party nominees.
That creates an interesting comparison with the Senate market: Polymarket has a Democrat slightly ahead in the district Hinson currently represents while simultaneously pricing Hinson as the statewide Senate favorite.
IA-3: Sarah Trone Garriott 76.5¢ vs. Zach Nunn 23.5¢. Nunn is the Republican incumbent and won the district 51.8% to 47.9% in 2024. Trone Garriott is challenging him in a district that has produced close elections in recent cycles.
IA-4: Dave Dawson 5.5¢ vs. Chris McGowan 94.5¢. This is the one part of the board that remains overwhelmingly Republican. The seat is open, with former state representative Dawson facing McGowan.
Taken together, the board is pricing a fairly significant Democratic improvement across Iowa while keeping Hinson favored in the highest-profile statewide federal race.
The Iowa Senate is the outlier
That’s ultimately the part worth watching.
Two reasonable interpretations explain the current numbers.
One is that the Senate market is correctly capturing something the vote-intention polls are missing: Hinson’s name recognition, Iowa’s recent Republican lean, differences in turnout and a meaningful group of Sand-Hinson ticket splitters.
The other is that the Senate contract has simply adjusted much less than the rest of the Iowa board to the state’s recent polling.
The next polls should help separate those explanations.
If more likely-voter surveys look like Emerson, with Sand ahead while Hinson maintains a Senate lead, the difference between the two contracts becomes easier to understand.
If more surveys look like Marist and begin putting Turek ahead while Sand remains strongly positioned, the gap between the Senate contract and the rest of the Iowa board becomes harder to ignore.
Iowa’s absentee voting period begins October 14, when county auditors can begin mailing ballots and voters can start casting absentee ballots in person.
By then, there should be much more evidence of whether Iowa is really preparing to split its statewide ticket, or whether one side of Polymarket’s Iowa board has been slower to adjust.
