Voters register as members of a party or as “blanks.” Parties make their own rules about who may vote in their primary, but right now except for the Independence Party, they all require registration in their party.
Any party whose gubernatorial candidate garnered 50,000 votes or more in the previous gubernatorial election is guaranteed a line on the general election ballot (and they are listed on the ballot in order of the number of votes their candidate for Governor received statewide).
Candidates must submit nominating petitions signed by voters registered in the party line they are seeking (the number depends on the number registered in that party in the area that the office represents). If more than one candidate from the same party submits qualified petitions there will be a primary. If the candidate is not a member of the party whose line s/he seeks s/he must get the permission of the party committee to run on that line (this is done with a Wilson-Pakula certificate).
Candidates may also submit nominating petitions to run on a party line that they create (usually only for that election). For first-time parties the petition signers are not required to be registered in that party, but may not have signed any other nominating petition for that office.
Candidates may also get onto the ballot by being nominated by a party convention or a party caucus.
Party members may also circulate petitions to create the opportunity to write in a name for an unspecified person for an office in which there is no contest for the party endorsement. This is known as “opportunity to ballot.”
In NYS candidates can be listed on the ballot multiple times (once for each party whose candidate they are). Candidates supported by several parties are called fusion candidates.
The Wilson-Pakula Law (1947) both requires that a candidate be a registered voter in the party whose nomination s/he seeks, and provides a way around this requirement with a Wilson-Pakula certificate.