Most state primaries are closed, so you have to register for a particular political party within an appropriate timeframe to be eligible to vote for a potential

Most state primaries are closed, so you have to register for a particular political party within an appropriate timeframe to be eligible to vote for a potential nominee. Both Ivanka and Eric Trump were too late to register as republicans and vote for their father in the New York primary. https://www.washingtonpost.com/news/post-politics/wp/2016/04/11/ivanka-and-eric-trump-didnt-register-in-time-to-vote-for-their-dad-in-new-york/ https://www.washingtonpost.com/news/post-politics/wp/2016/04...