I'm not a formal member of a party. Sadly, I think for so many, what binds them to a political party has less to do with the representation provided by that candidate / party and more to do with anger / hatred of a common enemy. I have seen this so often in real life... People who can't really pin down what it is about a candidate or platform plank that represents them, rather who the candidate / party is targeting that they dislike and how dangerous they believe that group to be.
Terrorists, militant radicals, illegals, the 1%, lobbyists, bankers, corrupt politicians, corrupt / abusive police, gays, religious kooks, there's a never ending list of boogie-men that need to be "shut down" and this candidate or that party is the 'only one' to do it. I see that pitch more often than a voter willing to specify how exactly a candidate or party is representing them and the principles they practice.