Election of the President of the United States is a multi-stage procedure and somewhat confusing in the eyes of an outsider. The main vote takes place every 4 years and is scheduled for the same day - the first Tuesday in November. On this day, citizens are offered a choice of several pairs of candidates (president + vice president). But formally, this is not yet the final vote, moreover, it is preceded by several preliminary ones, designed to narrow the range of potential candidates.
Formally, in the main vote, citizens do not vote for a specific potential president, but for a set of people ("electors") who receive instructions from their state to vote in a certain way at the electoral college. The number of such electors from each state is determined by the number of seats allocated to it in both houses of the US Congress. Regardless of how many percent a particular president and his deputy received in the vote, all electors from that state are required to vote only for the winner. Therefore, each party that nominates a presidential candidate prepares its own set of electors.
Now the number of these trusted people who must enter the electoral college is 538, so in order to win the tandem of future leaders of the country, 270 of them need to vote. The collegium will meet to elect the president on December 17, and the results will be calculated on January 7. But both of these actions will be nothing more than a formality - almost 3 months earlier it will already be known who is obliged to vote for whom.
The procedure for nominating presidential candidates from parties in the United States is also multi-stage, and it begins about a year and a half before the main elections. First, in each state, parties hold primary elections - "primaries". On them, ordinary members vote to determine their representatives at the regional party conference, where, in turn, delegates to the national conference of this party will be determined. And it is there that the delegates will vote for one of the candidates.
Each of these steps implies that the elected delegates are required to vote for a specific candidate. Therefore, it turns out that, despite the complexity of the procedure, it is at the very lowest stage that the future head of state is determined. But formally, only by gaining two-thirds of the votes at a national conference, a candidate candidate becomes the party's single nominee for the presidency. And he himself determines the candidacy of the future vice-president - this operation so far does without another multi-level voting process.