New Jersey Statutes Title 19. Elections 19 § 31-13.2

If, when submitting a voter registration form for any reason, a registrant declares thereon his or her political party affiliation and in so doing declares an affiliation with a political party other than the political party with which that person was affiliated previously, the registrant shall be ineligible to vote in the next succeeding primary election unless he or she has made the declaration of affiliation with the political party specified in the latest voter registration form no later than the 50th day next preceding such primary election.