Question: who determines the way in which primaries are set up

title: United States presidential primary
text: The presidential primary elections and caucuses held in the various states , the District of Columbia , and territories of the United States form part of the nominating process of candidates for United States presidential elections . The United States Constitution has never specified the process ; political parties have developed their own procedures over time . Some states hold only primary elections , some hold only caucuses , and others use a combination of both . These primaries and caucuses are staggered , generally beginning sometime in January or February , and ending about mid-June before the general election in November . State and local governments run the primary elections , while caucuses are private events that are directly run by the political parties themselves . A state 's primary election or caucus is usually an indirect election : instead of voters directly selecting a particular person running for President , they determine the number of delegates each party 's national convention will receive from their respective state . These delegates then in turn select their party 's presidential nominee . The first state in the United States to hold its presidential primary was New Hampshire in 1920 . 

Answer: answer: The United States Constitution has never specified the process; political parties have developed their own procedures over time.  Some states hold only primary elections, some hold only caucuses, and others use a combination of both.  State and local governments run the primary elections.