In presidential, state, and congressional primaries, voters must affiliate with a party to vote in their primary, but unaffiliated voters may affiliate with a party on election day. Affiliated voters wishing to update their affiliation must do so at least 15 days before an election. You can update your affiliation 3 months after the date of your last party change. 17-year-olds can in the primary election if they will be 18 by the corresponding general election.
