Government Relations Update 6.17.26

Written by Various BW Attorneys | Jun 18, 2026 12:44:43 PM

With Iowa’s primary elections and state party conventions concluded, the political landscape shifts entirely to the November general election. To help you track key battlegrounds, our team has analyzed the latest June voter registration data. The accompanying chart highlights the most competitive races based on raw registration numbers and percentage margins. Over the past three months, narrowing registration gaps across the state signal an increasingly competitive cycle.

The raw data reveals several interesting dynamics in key districts:

Iowa House: Out of the top 20 closest races as measured purely by voter registration totals, 13 involve incumbents and the top five districts each have less than a 500 voter registration difference. The closest (by a percentage of 2.17%) is District 73 where a Democrat incumbent (E. Wilson) serves in an area where Republicans enjoy a slim 277 voter registration advantage over Democrats. In another unique district, the Republican incumbent in House District 99 (M. Rinker) is defending his seat where Democrats currently hold an even slimmer 248 voter registration advantage over Republicans. On average, there are roughly 32,000 residents in each House district.
Iowa Senate: Eight of the top 10 closest Senate races as measured by voter registration totals feature incumbents. Notably, while in the House there are seven districts where the registration percentage difference between Democrats and Republicans is less than 5%, not a single Senate district falls below 5% (the closest being District 37, M. Donahue, where there is a 5.36% difference with Democrats holding a 1,291 voter registration advantage). In Senate Districts 1 (C. Drey) and 35 (M. Zimmer), Democratic incumbents are defending seats where Republicans currently hold the voter registration lead (1,517 and 4,238 respectively). Keep in mind, on average, there are roughly 65,000 residents in each Senate district.

Interestingly, several highly-competitive districts (as measured purely by voter registration numbers) currently involve uncontested seats this cycle:

House: Among the 20 House districts with the narrowest registration margins, five Democrats are running unopposed. Of those five districts, in Districts 73 (E. Wilson) and 27 (K. Judge), Republicans hold a voter registration advantage (217 and 1,372 respectively).
Senate: In the Senate, out of the 25 Senate seats on the ballot this year, 11 have no major-party challenger (five Republicans and six Democrats running unopposed).

Looking briefly at Iowa’s congressional districts, Republicans currently hold a voter registration lead in all four districts. In three districts, the registration gap is under 30,000 voters, representing a 7% to 9.95% margin.

Overall, many races are becoming increasingly competitive as voter registration margins have narrowed in many districts over the past several months. As November nears, our team will continue to share updates, including additional insight regarding fundraising amounts, cash on hand, voter registration changes, and more. Please don’t hesitate to reach out with any questions about any of these races or the upcoming elections generally.

Key

Red	Districts where Republicans lead in active voter registration contain cells that are highlighted in red. The “Registration Difference D&R” shows the GOP voter advantage.
Blue	Districts where Democrats lead in active voter registration contain cells that are highlighted in blue. The “Registration Difference D&R” shows the Democratic voter advantage.
"Incumbent"	Any candidates that are incumbents seeking re-election are noted as incumbents next to their party affiliation.

Governor

Candidates

No Party
Active

Democrat
Active

Republican

Active

Difference

R&D

Reg. Difference R&D

Zach Lahn (R) v. Rob Sand (D)

588,009

500,432

694,349

16.23%

193,917

Congress - House of Representatives

District	Candidates	No Party Active	Democrat Active	Republican Active	% Difference R&D	Reg. Difference R&D
1	Mariannette Miller-Meeks (R-Incumbent) v. Christina Bohannan (D)	158,254	135,953	161,765	8.67%	25,812
2	Joe Mitchell (R) v. Lindsay James (D)	156,668	132,773	162,106	9.95%	29,333
3	Zach Nunn (R-Incumbent) v. Sarah Trone Garriott (D)	145,231	141,332	163,019	7.13%	21,687
4	Chris McGowan (R) v. Dave Dawson (D)	127,856	90,374	207,459	39.31%	117,085

State Senate

District	Candidates	No Party Active	Democrat Active	Republican Active	% Difference R&D	Reg. Difference R&D
37	Randy Marzen (R) v. Molly Donahue (D-Incumbent)	13,905	12,688	11,397	5.36%	1,291
1	Christopher Prosch (R) v. Catelin Drey (D-Incumbent)	7,664	7,393	8,910	9.31%	1,517
21	John Hollinrake (R) v. Heather Matson (D)	15,392	12,553	15,698	11.13%	3,145
41	Kerry Gruenhagen (R-Incumbent) v. Tom Wieck (D)	13,284	9,934	12,462	11.29%	2,528
49	Cynthia Mensendick (R) v. Cindy Winckler (D- Incumbent)	11,653	10,921	7,802	16.66%	3,119
47	Scott Webster (R- Incumbent) v. Nikhil Wagle (D)	15,637	10,506	15,122	18.01%	4,616
35	Joe Stutting (R) v. Mike Zimmer (D- Incumbent)	13,883	9,258	13,496	18.63%	4,238
25	No (R) Challenger v. Herman Quirmbach (D-Incumbent)	11,551	10,911	6,910	22.45%	4,001
31	No (R) Challenger v. Timi Brown Powers (D)	8,892	11,381	7,072	23.35%	4,309
39	No (R) Challenger v. Liz Bennett (D- Incumbent)	11,172	12,803	7,281	27.49%	5,522

State House

District	Candidates	No Party Active	Democrat Active	Republican Active	% Difference R&D	Reg. Difference R&D
73	No (R) Challenger v. Elizabeth Wilson (D-Incumbent)	7,486	6,245	6,522	2.17%	277
99	Matthew Rinker (R-Incumbent) v. Jennifer Kirkman (D)	5,964	5,516	5,268	2.30%	248
80	No (R) Challenger v. Aime Wichtendahl (D-Incumbent)	6,760	6,542	6,121	3.32%	421
59	Christian Hermanson (R- Incumbent) v. Jacob Welper (D)	6,505	5,235	5,715	4.38%	480
81	Dillon Fillion (R) v. Daniel Gosa (D-Incumbent)	6,460	5,544	5,076	4.41%	468
44	No (R) Challenger v. Larry McBurney (D-Incumbent)	5,755	6,814	6,217	4.58%	597
40	Bill Gustoff (R-Incumbent) v. Heather Sievers (D)	6,782	5,890	6,504	4.95%	614
43	Nicole Hasso (R) v. Jill Alesch (D)	6,618	6,585	7,286	5.05%	701
75	No (R) Challenger v. Drew Stensland (D)	5,975	5,993	5,399	5.21%	594
52	David Blom (R-Incumbent) v. Mike Tupper (D)	4,734	4,357	4,935	6.22%	578
1	Josh Steinhoff (R) v. Shawn Olorundami (D)	3,463	3,608	3,184	6.24%	424
100	Blaine Watkins (R-Incumbent) v. Matthew Morhrfeld (D)	5,597	5,027	5,700	6.27%	673
72	Jennifer Smith (R-Incumbent) v. Matt Robinson (D)	5,342	6,865	5,983	6.86%	882
31	Kevin DuBay (R) v. Mary Madison (D-Incumbent)	6,117	7,194	6,245	7.06%	949
39	Troy Clark (R) v. Nate Boulton (D)	5,251	5,864	5,004	7.61%	860
69	Tom Determann (R-Incumbent) v. Mandy Meier (D)	6,613	4,833	5,689	8.14%	856
98	Nathan Ramker (R) v. Andrew Fitzgerland (D)	6,083	5,063	4,243	8.81%	820
42	Heather Stephenson (R) v. Amy Tagliareni (D)	6,896	5,914	7,094	9.07%	1,180
27	No (R) Challenger v. Kenan Judge (D-Incumbent)	9,002	6,691	8,063	9.30%	1,372
20	Keith Jones (R) v. Eric Armstrong (D)	4,337	3,931	4,809	10.05%	878

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