Romney supporting Ernst for Iowa seat in U.S. Senate

Former Republican presidential nominee Mitt Romney is supporting Iowa Sen. Joni Ernst's campaign for the party's U.S. Senate nomination.

In an email Tuesday, Romney praised Ernst repeatedly as a "proven conservative," highlighting her fiscal record in the state Legislature and her military service.

In addition to serving in the state Senate, Ernst is a lieutenant colonel in the Iowa Army National Guard.

"As a mother, soldier and proven conservative, Joni has the kind of experience, skillset and discipline it will take to not only win this important seat, but to also take Iowa values to help turn around the mess in Washington," the email said.

The email calls Ernst a "proven conservative" three times and asks for campaign donations.

The support could provide a boost to Ernst's campaign. Recent polls have said that retired utility executive Mark Jacobs is leading the five-way race.

In addition to Ernst and Jacobs, college professor and radio talk show host Sam Clovis, former U.S. Attorney Matt Whitaker and auto dealer Scott Schaben are all campaigning for the GOP nomination.

The primary will be in June.