Republican candidates in marquee Senate races have welcomed Thune's help as he's traveled around the country in the weeks before the midterm elections, scrambling to save his majority.

It's been more than a decade since Iowa has had a Democratic governor or senator. But this year, with the incumbents retiring, both races are competitive. As Peter Tubbs at Iowa PBS reports, record-high diesel prices have hit the state's agriculture industry particularly hard and could influence the midterm elections.