If you are a previously affiliated voter who becomes unaffiliated, you must file the declaration form no later than 55 days before the primary in order to vote in either primary.
Declaration must be filed no later than 55 days preceding the primary in which the voter wishes to vote. A newly registered voter, an unaffiliated voter or a voter who has never voted in a primary election, can affiliate with the Democratic or Republican Party on the day of the primary.
Mercer County Supt. of Elections
640 South Broad St.
PO Box 8068
Trenton, NJ 08650-0068