who can vote in PA primary elections?
1 A registered voter may vote in any party primary regardless of his own party affiliation. 2  When voters do not register with a party before the primary, it is called a pick-a-party primary because the voter can select which party's primary he or she wishes to vote in on election day. primary election is an election that narrows the field of candidates before an election for office. Primary elections are one means by which a political party or a political alliance nominates candidates for an upcoming general election or by-election.