Final answer:
Delegates in primaries are primarily distributed according to party rules. These rules are determined by political parties, which can adjust delegate counts based on registered party voters, timing of primaries, and other considerations, shaping the influence of states in presidential nominee selection.
Step-by-step explanation:
What determines how delegates are distributed by the primaries is primarily determined by party rules. Political parties allot delegates to their national nominating conventions based largely on the number of registered party voters in each state. For instance, the Democratic Party sent 494 delegates from California due to its large number of Democrat voters, whereas Wyoming with fewer Democrat voters sent only 14 delegates to the 2020 Democratic National Convention.
The national political parties have the authority to modify the delegate count which can increase or reduce a state's influence in the presidential nominee selection process. This was seen when the Republicans gave bonus delegates to states that held their primaries and caucuses later in the nominating season in 1996, or when both major parties penalized Michigan and Florida by reducing their number of delegates for holding early primaries in 2008.
The primary system functions as a test of candidates' popular appeal, engaging voters in either a primary election or a caucus. Some primaries employ a 'winner-takes-all' approach for delegates, while others use a proportional distribution based on voter support. A candidate must garner enough delegates through primaries or caucuses to secure their party's nomination.