For the first time since losing the 2012 presidential election to Barack Obama, Mitt Romney returned to Iowa on Friday to stump for Senate candidate Joni Ernst. Romney said he's opening his campaign donor list to Ernst, who is a farmer and national guard officer. Ernst has built a lead in the five-way race for a GOP nomination to go against Democratic U.S. Representative Bruce Baley in the competition for the seat vacated by five-term Democratic Senator Tom Harkin, who is not seeking re-election. "By indicating my support for Joni as well as some other candidates from around the country we're encouraging donors to help these candidates," Romney told The Associated Press. "Part of endorsing someone is letting the people who know, and who like me, to get involved in the campaign."