Zach Lahn won the Republican primary for Iowa governor on Tuesday, defeating Rep. Randy Feenstra in a race that marks President Trump's first major primary loss of the 2026 midterm election cycle. The result breaks Trump's winning streak on endorsements during this election season, as every candidate he backed since March had previously won their primary contests.
Feenstra had secured Trump's endorsement ahead of the race, making his second-place finish particularly significant as a test of the president's influence within Republican politics. Five candidates competed for the Republican nomination in Iowa's governor's race, with Lahn emerging as the victor.
The gubernatorial contest takes on added importance given that Iowa has been a Republican stronghold, with the party controlling the governor's mansion since 2011. Democrats believe they have a strong candidate in Rob Sand, the state auditor and the last member of his party holding statewide elected office. Sand ran unopposed in the Democratic primary.
Iowa's primary results on Tuesday set the stage for months of campaigning ahead of the November general election, which could significantly influence the balance of power in Congress and control of statehouses. While Iowa has leaned Republican for the past decade, Democrats see opportunities to be competitive in multiple races across the state, including three of its four House seats and the Senate election to replace retiring Republican senator Joni Ernst.
In the Senate race, Josh Turek, a state house representative who benefited from millions of dollars in outside spending and support from major Democratic figures, won the Democratic primary. He defeated Zach Wahls, a state senator who positioned himself as an outsider challenging party establishment figures. The contest became contentious, with Wahls arguing that Turek represented Democratic elites while claiming to offer voters a different direction for the party.
On the Republican side, Ashley Hinson, a U.S. representative backed by Trump, won her primary to face the Democratic Senate nominee. Hinson will attempt to replace Ernst in November.
In House races, vulnerable Republican incumbent Mariannette Miller-Meeks won her primary in southeastern Iowa's first district and will face Democrat Christina Bohannan in a rematch. Bohannan narrowly lost to Miller-Meeks in 2024 by approximately 800 votes. In Iowa's third district, incumbent Zach Nunn won the Republican primary, while Democrat Sarah Trone Garriott secured the Democratic nomination.
The Iowa primary results demonstrate that while Trump's endorsement remains valuable to many Republican candidates, it does not guarantee victory even within Republican primaries. The governor's race in particular underscores the diversity of opinion within the party as it heads into the 2026 midterm elections.