DES MOINES, Iowa (AP) – Former Republican presidential nominee Mitt Romney is backing state Sen. Joni Ernst in the crowded GOP primary for Iowa’s open U.S. Senate seat. In a Wednesday press release from Ernst, Romney calls the lawmaker from Red Oak “a proven conservative with a great record.”

Ernst is among six Republicans running in the June 3 primary. The others include radio host Sam Clovis, businessman Mark Jacobs, former U.S. Attorney Matt Whitaker and lesser-known candidates Paul Lunde and Scott Schaben. They are vying to run against U.S. Rep. Bruce Braley of Waterloo, the only Democrat running for the seat now held by Democrat Tom Harkin, who is not seeking a sixth term in November.

Romney campaigned aggressively for Iowa in the 2012 election but lost the state to President Barack Obama.