Zach Nunn (R-inc.) vs. Sarah Trone Garriott (D)
I. The Race
Zach Nunn (Republican) is an Air Force Reserve Colonel with serious combat experience. He was once a member of the Iowa legislature, and has represented IA-3 since first being elected in the 2022 GOP House victory and now seeks his third term.
Sarah Trone Garriott (Democrat) is an Iowa state senator with a background in religious studies. She is running a “kitchen table” campaign that is relatively careful about not becoming “Trump-centered,” with the understanding that Iowa supported Trump by a wide margin. This is her first attempt at Congress.
II. District Geography
Iowa’s 3rd Congressional District (IA-3) occupies the southwestern portion of the state (all but the very corner), and contains the capital city of Des Moines and its most electorally significant suburban areas – and a total of 21 counties. Since Iowa doesn’t gerrymander, this seat (just like IA-1) is extremely competitive. A Republican state that wanted to win would figure out how to split half of Des Moines into IA-4, which is overwhelmingly red. As such, the clash between urban/suburban and farmland produces tight margins in presidential and House elections. Here is how President Trump fared in all three of his races in the current boundaries of IA-3:
IA-3 sits well to the left of the state as a whole. Trump had to carry Iowa by over 13 points in 2024 just to take IA-3 by 4.3%; he hasn’t been helped by the suburban drift of Dallas County, which is just west of Polk County (Des Moines), that has taken place over the past decade. The rurals are about volume of turnout. The metropolitan Des Moines area is about persuasion.
III. Market Assessment
Polymarket bettors overwhelmingly favor Trone Garriott, who is vastly overpriced.
IV. History
Des Moines and the rest of Iowa’s districts have moved around a lot in recent decades. In 2010, the last election of the first decade of the 21st century, Iowa’s U.S. House map looked like this:
Iowa lost an electoral vote going into the next decade and then split its lines in a different pattern, putting Des Moines and IA-3 into a district more closely resembling the one Nunn is defending now. Republican David Young, running for reelection alongside President Trump’s first campaign in Iowa, won his 2016 race by 13.7%. Young then turned around in 2018 and lost the seat by 2.2% to Cindy Axne, who proceeded to narrowly defeat him in a 2020 rematch.
IA-3 met the key warning sign for a 2018 flip – a seat with a major metropolitan area in which President Trump massively underperformed the Republican House candidate. The districts were redrawn yet again, and in their current form, Nunn knocked Axne out in the 2022 GOP House takeover, and by a very narrow margin of just 0.7%:
Thanks to Trump’s statewide blowout, Nunn ran up a very impressive margin compared to what IA-3 is normally capable of:
Nunn must hope that rural turnout is overwhelming knowing just how strong the shift in metropolitan Des Moines was in 2018.
V. Analysis of 2026 Primary Results
Neither Nunn nor Trone Garriott faced a serious primary challenger; therefore, there is no lingering drama impacting either party for the General Election.
VI. Polls
No mainstream polls have run for this race since March.
VII. Media Ratings
Every major reviewer favors Trone Garriott; Inside Elections is the only one thinking it may come down to the wire.
VIII. Party Registration
While Republicans have a larger numerical advantage over Democrats today than they did in November 2024, this isn’t the case in IA-3. Democrats have made up 3,129 net registrations, dropping the Republican advantage by a full point. Most of this damage has been sustained in Polk County, where Democrats have out-registered Republicans roughly two to one. Unlike cases in which a registration gain is tied to roll maintenance, this is a legitimate Democrat gain.
IX. Election Considerations
This is what I had to say about Iowa’s elections in my IA-1 piece:
One thing is for certain, and that is that Iowa runs excellent elections. A lot of this is owed to the current treasurer, Roby Smith, who started turning the screws on election reforms as a state legislator before the 2020 election. Iowa has manageable early voting windows, control over the mail-in balloting process, and a voter registration system that doesn’t automatically register voters.
X. Summary and Election Estimate
Nunn is sitting in a seat that, much like AZ-1, has stabilized its political leanings. Trump underperformed in the old boundaries in 2016 relative to the GOP representative, and that representative was bounced in 2018 when the “suburban swing” bill came due.
My proprietary mapping of IA-3 above shows a zoomed-in bubble of Polk County and the eastern edge of Dallas County, which contains key suburban territory Nunn will need to hold his ground in. Any suburban swing, plus high turnout in core Des Moines in the blue-coded (“Democrat”) precincts combined with lagging rural turnout puts this election on ice and gives Democrats a key flip in what is one of the most important races for the House majority.
The decision matrix favors Trone Garriott:
Based on the established swing of IA-3 and the Des Moines metro in the first Trump midterm, legitimate Democrat gains in voter registration, and Trone Garriott’s money advantage, I consider her the favorite. I would normally be inclined to rate her at 65/35, but given Nunn’s popularity, success, and early voting splits similar to his 2024 win, I think he has a better-than-normal chance to hold the seat – certainly much better odds than Mariannette Miller-Meeks has to hold IA-1.
Forecast for IA-3 House
Seth Keshel, MBA is a Senior Fellow at the Gold Institute for International Strategy and a retired Army Captain. He publishes Captain K’s Corner on Substack.
