Each political party has the option of allowing people who register to vote without stating a political party preference ("no party preference" voters, formerly "decline-to-state" voters) to vote in their presidential primary election. 

Are you a “no party preference” voter?

If you checked “I do not want to disclose a political party preference” on the voter registration form, you will not get a ballot containing the names of candidates running for president. Your ballot will contain all other races and ballot measures.

You can request the ballot of one of the following parties when you are at the polling place (or in your request for a vote-by-mail ballot from your county elections office):

-American Independent Party

-Democratic Party

-Libertarian Party

More info on no party preference.

Do you want to vote for the Green, Peace and Freedom, or Republican presidential candidates?

To vote for these candidates, voters must be registered with their respective parties.
 

How can I change my registration or register to vote?

You can register to vote OR re-register to vote in the political party of your choice before May 23 online: www.registertovote.ca.gov