How Idaho’s Primary Election System Works

Idaho uses a partially closed primary system, meaning voters must be registered with a political party in advance to vote in that party’s primary. However, Idaho also allows unaffiliated voters to participate by choosing a party ballot at the polling place in some primary elections, depending on current state rules and party participation.

In practice, voters select either a Democratic, Republican, or other available party primary ballot, but they may only vote in one party’s primary during each election cycle. Idaho’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.

Idaho does not use statewide primary runoff elections; instead, the candidate with the most votes in each primary wins the nomination.