The US Constitution describes procedures for Presidential elections, but it does not stipulate how presidential candidates are selected. The Parties have developed a unique system to choose over a period of months their nominees through Primaries, individual elections or caucuses in each state with each Primary electing delegates who will gather together at the Party's Convention to officially select their Presidential Candidate. After the Convention, each confirmed Presidential Candidate will select a Vice-President, and the two will run together as a single ticket in the general election in November.
The Primaries are managed in part by the Parties and in part by State Governments, the latter determine who will be included on Presidential ballots for the presidential election in their state, but procedures vary widely from one state to the next.
What is a caucus? Party supporters meet in person with voters who through discussion come to a selection of the winning candidate for that particular group. This informal process, which used to be generalized, has been increasingly replaced by secret ballot elections, so that today only a few states retain caucuses: Iowa, Nevada, North Dakota and Wyoming.
Presidential Primary Elections take a wide variety of forms, including: i) Partially or totally Closed (20 states + Washington DC) require that the voter be registered as a Party member prior to the election, ii) Partially Open (15 states), where Party members and un-affiliation persons can vote, iii) Fully Open (16 states), where any voter can vote. In allocating delegates some states use winner-take-all Primaries (more Republican primaries), where the candidate that receives the most votes gets all of that state's delegates, others use proportional voting (more Democratic primaries), where candidates receive delegates in proportion to the percentage of votes they receive, or there is a mix of proportional with a minimum percentage to win delegates.
Voter turnout in Primaries is much lower than in Presidential elections: in 2016 and 2020, about 25% of eligible voters participated in Primaries as compared to 66% for the 2020 Presidential election. Also, voters in Primary elections have a different profile from the general election, they are older, wealthier and generally represent the more radical positions held by their Party.
When a first-term President is seeking re-election as was the case for Trump in 2020 and is the case for Biden in 2024, the President normally controls the Party and is expected to easily win the nomination, but for all other cases, candidates go through the long (January-July), arduous process with massive media coverage for a large list of initial candidates to be gradually reduced to the winning candidate (there were 29 Democratic candidates at the beginning of the process in 2020, there are currently 11 candidates for the Republican nomination in 2024).
There can be major swings in momentum from one candidate to another during the long Primary season, which begins with the Iowa caucus (on January 15, 2024) and continues with the first Primary in New Hampshire (January 23, 2024), two states that have a mix of population not typical of the average in the U.S. The impact of results in Iowa and New Hampshire is great due to their early timing and intense media coverage, but winning in Iowa, for example, is a poor prediction for the eventual winner.
There is one date, March 5, 2024, termed "Super Tuesday", when on a single day about one-third of the delegates will be elected, usually clarifying the picture of the future winner. The final candidate selection is confirmed only at each Party's National Convention, when the winner must receive a majority of delegate votes. The Republican Party National Convention will be in Milwaukee, Wisconsin July 15-18, 2024; the winning candidate will need to receive 1,234 votes from the 2,467 elected delegates. The Democratic Party National Convention is in Chicago, Illinois August 19-22, 2024; a candidate will need to win 1886 votes from the 3770 elected delegates.
Although it has not happened since 1952, it is possible for no majority winner of delegates to emerge from the Primary season, at which time the Party in question approaches its National Convention with uncertainty, leading to what is referred to as a Contested or Brokered Convention, with multiple ballots to select the winner, a situation that is highly unlikely to occur for either Party in 2024.
 Including states with caucuses
Patrick Siegler-Lathrop is a dual-national American-French businessman living in Portugal, having pursued a career as an international investment banker, an entrepreneur-industrialist, a university professor and a consultant. He is the author of numerous articles on the US and a book, "Rendez-Vous with America, an Explanation of the US Election System". He is currently the President of the American Club of Lisbon, a 76-year old organization "promoting goodwill and understanding between people and cultures". For more information: https://RendezVouswithAmerica.com
The opinions expressed herein are personal and not those of the American Club of Lisbon.