You're looking at things too logically. You need to think like a liberal (I know, that's an oxymoron). They don't give a rat's behind how bad he is they still think he is better than any Republican. I'd love to be wrong on this but I've seen too many libs reject a solid Republican challenger and vote instead to reelect liberal democrat trash. Of course, only time will tell.
Most likely they will stay home next November. Forgot to add that.
It is called getting discouraged.