Nominees for the presidency of the two major parties are chosen by delegates at national conventions. How these delegates are chosen varies across states and between the political parties.

A primary election (primary nomination), or simply primary, is an election in which voters under a jurisdiction select the candidate that a party will present to a subsequent public election. In other words, it is a democratic way to pre-select the candidate that a party will present to a particular electoral process. The "Primary" are more common in the United States, not only for presidential elections but also to choose candidates for representatives, senators, mayors and governors, among others and their origins date back to the progressive movement. The first party to carry them out was the Progressive Party, by Theodore Roosevelt, and was followed by the Democratic and Republican parties. Even the minority Communist Party of the USA. UU. He accepted the regime of the primaries, obtaining a positive vote of six voters in 1948 in Massachusetts. There, the primary elections are held by the government on behalf of the parties [citation needed]. In the rest of the world, the nomination of presidential candidates is generally the responsibility of political parties and organizations and does not include the general public.

In addition to the primaries, another of the ways to select a candidate is caucuses or assemblies, conventions, and nominations at meetings. Historically, the political parties of Canada to their candidates in the meetings of the parties in each constituency. The leaders of Canada are elected in leadership conventions, although some parties have abandoned this practice in favor of a militant system, a vote.