If either one or two candidates is dominating the field at the time of the first primaries and caucuses, the voters are superfluous because the victor is already guaranteed. If, however, no candidate is dominant, then the primaries and caucuses will determine the winner. Nonetheless, in recent campaign cycles, that determination has been made earlier and earlier in the process, by fewer and fewer voters, who pick from only a few candidates - the ones who have not already eliminated themselves from serious contention by their weak performances in the pre-primary phase.
Roger Lawrence Butler, Claiming the Mantle: How Presidential Nominations Are Won and Lost Before the Votes Are Cast
democracy, nominations, political-parties, political-science, presidents, primaries