Retiring Sen. Joni Ernst, R-Iowa, endorsed Rep. Ashley Hinson, R-Iowa, on Saturday in the race to succeed her, a move Republicans are treating as a step toward locking down a high-profile open-seat contest as Democrats try to broaden the 2026 map.

Ernst formally endorsed Hinson during a campaign stop in Adel, west of Des Moines, where Hinson held an event at Spring Manufacturing, according to The Gazette.

The endorsement adds a high-profile in-state boost to Hinson's bid as national Republicans work to avoid a costly primary and keep the seat in GOP hands.

Hinson launched her Senate campaign in September 2025, after Ernst announced she would step aside.

Hinson is also backed by President Donald Trump, who endorsed her in September 2025.

On the Republican side, former state lawmaker Jim Carlin is also running.

Democrats, meanwhile, have sought to frame the race around costs and health care, pushing back on Republican efforts to present the seat as safely in the GOP column.

In a statement from Iowa Democratic Party spokesperson Paige Godden criticizing both Ernst and Hinson, argued that the two Republicans share the same priorities.

The Democratic primary field includes state Sen. Zach Wahls, state Rep. Josh Turek, former chamber of commerce leader Nathan Sage, and veterans advocate Bob Krause.

Ernst's retirement announcement in 2025 drew national attention because it created an open Senate seat in a state that has favored Republicans in recent cycles.

Reuters reported at the time that Ernst stepping aside could complicate Republicans' efforts to maintain control of the Senate, though it also noted the seat was rated "Likely Republican" by the Cook Political Report.

Iowa's primary is June 2, with the general election set for Nov. 3.