Fundamentally, voters answer 3 basic questions in an election.
A: Do you want "more of the same" ?
B: Do you want something "a little different"?
C: Do you want something "completely different"?
These questions carry the highest stakes for Americans in Presidential contests, but they are applicable all the way down the scale. And for so-called "one issue" voters, the overlapping congruities and paradoxes of other tangential issues can complicate or sharpen the contrasts between the choices.
The most under-reported "secret truth" about American voters is that they more often than not, vote "against" a candidate, than actually voting "for" the candidate of their choice. In other words, the voter is more motivated by their opposition to a particular candidate because of that candidate's positions, record (resume'/character), and most importantly, the kinds of people who support that candidate, than they are compelled to vote for a particular candidate "on their side".
A psychological version of "the enemy of my enemy is my friend" adage, voters sublimate the negatives of the candidate they come to support because of their hatred/loathing of those who oppose that candidate.
This complex psycho-drama serves to consistently enable a continuity and stability of policy, for good and bad. But it also perpetuates tragic consequences, in the form of a majority or substantial plurality finding after the fact that:
They voted for C, but got B.
And all too often even worse, they voted for C and got A.