Idaho has semi-open and closed primaries. Voters registered with a particular party may only vote in that party's primary. A voter may only participate in the primary election of the political party for which they are registered, unless a party allows unaffiliated voters and/or voters registered with other parties to also participate in their primary. Unaffiliated voters can participate in all congressional and state primaries as well as Democratic presidential primaries, but only registered Republicans can participate in Republican presidential primaries. 17-year-olds cannot vote in the primary election if they will be 18 by the corresponding general election.
Idaho has semi-open and closed primaries. Voters registered with a particular party may only vote in that party's primary. A voter may only participate in the primary election of the political party for which they are registered, unless a party allows unaffiliated voters and/or voters registered with other parties to also participate in their primary. 17-year-olds cannot vote in the primary election if they will be 18 by the corresponding general election.