How Iowa’s Primary Election System Works

Iowa uses a partially open primary system, meaning voters do not have to be registered with a political party in advance to participate in a primary election. Unaffiliated voters may choose a Democratic or Republican ballot at the polling place and will have their voter registration updated accordingly.

Voters who are already registered with a political party may only vote in that party’s primary unless they change their registration before voting. Iowa’s primaries are used to select each party’s nominees for offices such as U.S. Senate, U.S. House, governor, statewide offices, and state and local positions.

Iowa does not use statewide primary runoff elections; instead, the candidate with the most votes in each primary wins the party’s nomination for the general election.