Candidates in Iowa’s crucial and competitive U.S. Senate race were on the move Tuesday as they kicked off the final sprint to the Nov. 3 election.Democratic challenger Theresa Greenfield embarked on a statewide bus tour that will continue to Election Day, and Republican incumbent Joni Ernst was on her way to Omaha, where she was set to appear at a campaign event with President Donald Trump.Ernst and Greenfield are locked in a close race, according to polling data.