Having been involved those choosing the party positions often are secretly voting third party. They are trying to change the party potition and when it works the vote for the party, but when it fails they vote for who they like.
people who only vote in the general election, and maybe the primaries have choosen their party and then potitions based on the party.
In New York many elections are so lopsided that I'm inclined to vote third party because voting either D or R if I don't like the candidate is "wasting my vote".
I was active in the Green Party (twisting people's arms to run for local office) in the early 2000s and think about voting Green in each presidential election but it's been a while because I don't particularly like Jill Stein and think if you're hard on CO2 you should be easy on Uranium.
people who only vote in the general election, and maybe the primaries have choosen their party and then potitions based on the party.