Chris Hayes: What Line Does Trump Have to Cross to Lose GOP Support?

HAYES: "As a general principle here, it does seem to me that perhaps one’s duty to one’s party and some moral commitments that a politician might have seem to be in conflict… There are certain things that, say, a nominee of the party you support would say or support that would be out past what you could in good conscience continue to support? What is that line? If it has not been crossed yet, what could conceivably be the line that could cross that?"