U.S. presidential primary

The series of presidential primary elections and caucuses held in each U.S. state and territory forms part of the nominating process of 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 in either late-January or early-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 union to hold its presidential primary was New Hampshire in 1920.

Each party determines how many delegates it allocates to each state. Along with those "pledged" delegates chosen during the primaries and caucuses, state delegations to both the Democratic and Republican conventions also include "unpledged" delegates who have a vote. For Republicans, they consist of the three top party officials who serve At Large from each state and territory. Democrats have a more expansive group of unpledged delegates called "superdelegates", who are party leaders and elected officials (PLEO). If no single candidate has secured an absolute majority of delegates (including both pledged and unpledged), then a "brokered convention" occurs: all pledged delegates are "released" after the first round of voting and are able to switch their allegiance to a different candidate, and then additional rounds take place until there is a winner with an absolute majority.

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