Smart Republicans.... there are a few.

[CapnAwesome]

Will there be a breaking point? Where it's safe enough that a cascade of Republican Congressmen/Senators will follow suit?

Hope so.

I don't think many will support Hillary, could be a few will defect to not voting or Gary Johnson as Mitt Romney said he was considering. If Johnson gets to 15% in the polls, which he is almost at and gets in the debates he is sure to take more votes from Trump then Clinton. There is always a few in either party who defect one way or another, though the lack of support for Donald Trump in his own party is pretty unprecedented.