The Iowa primaries are Tuesday, June 3. Voter turnout for midterm elections is dismally low, but the turnout for midterm primaries is even worse. Consequently, incumbents are all but guaranteed advancement to the general election. To add an additional layer of protection for incumbents' re-election, Iowa primaries are closed - meaning that only people registered to vote as Democrats and Republicans can participate in their respective party's primary.
Check out the listings of the candidates who will be on the ballots on June 3 for Republicans (RCReader.com/y/2014R) and Democrats (RCReader.com/y/2014D). Note that out of 25 seats up for election on the Democratic ticket, only two are contested in the primary. If you don't live inside state Senate District 45 (where Mark Riley is challenging incumbent Joe Seng) or in state Representative District 97 (where Carol Bohel and Jay Saxon are running to fill an empty seat), there are no races on the Democratic primary ballot in which casting a vote matters. And there is no candidate for county treasurer or District 94 state representative on the Democratic primary ballot.