I believe they have a psychological need to believe things that Hillary says and disbelieve what Trump says. Believing as they do supports their need to be “special snowflakes” who are “more moral” than the rest of us.
Being liberal is, in their minds, a sign of selflessness(!!!!) and altruism (sorry - forgot the barf alert).
So when they come face to face with the truth, many are so threatened by not being right, pure, etc. that they cover their ears and start screaming “LIAR!” and “RACIST!” etc. Sometimes you see them wake up and if so, they walk around depressed because information seems to point to them being a (moral) legend in their own mind. SOme come out of that depression by rationalizing “Well ok, she lied about that but only because the repubs made her do it” or “Okay but Trump is WORSE!”
I have a hard time thinking about all that has been released vi Wikileaks and there’s still a “race” on? ALl that she did and they don’t care? Ah, but it’s themselves they care about. They are going to “lie for the team” so they can pretend they were never on the wrong team to begin with.