The major parties select their presidential nominee at their national conventions, held every four years. At the conventions, delegates from each state vote and whichever candidate wins a majority of delegates becomes the party’s nominee. To win delegates, candidates compete in primary elections, held in each state prior to the convention. Primary races are usually hotly contested.
Because citizens get to vote in the primaries, they have a large role in the election. Prior to the 1972 election, voters played little role in selecting the party nominees, but that is not the case anymore. Before acquiring the party nomination, a presidential candidate must prove that he or she can attract voters by winning primaries.