A caucus is a meeting of party members or leaders to select nominees for public office and to conduct other party business. In the presidential nominating process, it is often used in combination with a state convention to elect delegates to the national nominating convention. Approximately twelve states use a caucus or convention system (or both) for choosing delegates, and each state’s parties and legislature regulate the methods used. The caucus or convention is the oldest method of choosing delegates, and it differs from the primary system because its focus is on party organization.