Voters in Iowa Senate district 1 will elect a successor to Republican State Senator Rocky De Witt on Tuesday, August 26. Governor Kim Reynolds scheduled the special election after De Witt died of cancer last week.

Although Donald Trump comfortably carried Senate district 1 in the 2024 presidential election, this seat should be highly competitive in a low-turnout special election environment.

Following De Witt’s passing, Republicans hold 33 Iowa Senate seats, and Democrats hold 16 seats. The difference between a 34-16 majority and a 33-17 majority may seem inconsequential, but it would matter a great deal when the Senate considers the governor’s nominees during the 2026 legislative session. Flipping the seat would enable Democrats to block some of Reynolds’ most controversial appointments, who need a two-thirds majority vote to be confirmed.

Iowa Senate district 1 covers most of Sioux City (other than the Morningside area on the south side) and some other parts of Woodbury County, including the small town of Lawton.

Voter registration totals favor the GOP. Senate district 1 contains 7,356 active registered Democrats, 8,993 Republicans, and 6,786 no-party voters, according to the latest official figures from the Iowa Secretary of State. The disparity among total registered voters (including “inactive” ones who did not participate in the 2024 general election) is smaller: 9,836 registered Democrats, 10,715 Republicans, and 10,833 no-party voters.

Recent voting history also favors Republicans. De Witt defeated Democratic State Senator Jackie Smith in the 2022 general election by 7,700 votes to 6,256 (55.1 percent to 44.7 percent), following an expensive campaign. Residents of the precincts now part of Senate district 1 preferred Donald Trump to Joe Biden in the 2020 presidential election by 50.4 percent to 47.6 percent. Trump’s margin of victory here widened in 2024; the Republican received 54.7 percent of the presidential vote to 43.4 percent for Kamala Harris.

That backdrop doesn’t sound promising. But Iowa Democratic candidates have had huge overperformances in all three special legislative elections so far in 2025:

• Mike Zimmer won by 3.6 points in Senate district 35, which Trump had carried by 21 points in November.
• Nannette Griffin lost by 3.2 points in House district 100, which Trump had carried by 27 points in November.
• Angel Ramirez won by 58 points in House district 78, which Harris had carried by 34.5 percent in November.

So with a good candidate and a strong ground game, Senate district 1 is very winnable for a Democrat. Republicans will spend heavily to keep that from happening, but turnout for an August election will likely be low.

Both parties will choose their nominees at special district conventions, which have not yet been scheduled. John Herrig, who ran for Woodbury County supervisor in 2024, emailed the county’s Democratic delegates on June 30 to say he would seek the party’s nomination. He is a 30-year member of the Machinists Union (now retired) who spent eighteen years as business representative of the International Association of Machinists and Aerospace Workers, District 6. Local Democrats have also mentioned Sioux City School Board member Treyla Lee as a possible candidate.

When an Iowa Senate seat becomes vacant, the state House members from that area sometime try to move across the rotunda. But Democratic State Representative J.D. Scholten, who represents the western part of Sioux City, is running for U.S. Senate in 2026. I haven’t head back from Republican State Representative Bob Henderson, whose district covers the other half of Senate district 1.

Please let me know of other contenders for this special election. I’ll update this post as needed.

UPDATE: Catelin Drey, a longtime Sioux City resident and grassroots organizer, has also contacted Democratic delegates about running in the special election and has a campaign website online already.

Independent candidates could also attempt to qualify for the ballot; it’s easy to collect 100 signatures on petitions from eligible voters in the district. Candidates must submit their nominating paperwork to the Iowa Secretary of State’s office by Friday, August 1 at 5:00 PM.