In addition to a primary, political parties can nominate candidates for general election through a petition or a vote of party leaders. caucus or a convention. signature drive or a public rally. referendum or a ballot initiative.

The main other way, rather than a primary, is a caucus, which is held during a nominating convention (so the correct answer is:"caucus or a convention"). A primary is a state-wide vote while the caucus is limited to the members of the party and only the people participating the caucus are invited to vote