Which Republican Senator is the most likely to get blanched?

[coloradocowboi]

I suspect that barring a hard right turn by Gardner or Ernst, either one will hold on.  Tillis is probably the answer, but there's no guarantee he would lose reelection.

This plays very, very poorly in CO:

http://www.denverpost.com/2017/02/03/cory-gardners-claim-of-paid-protesters-calling-his-office-2-letters/

He won't be "Blanched," but there is absolutely no way he wins in 2020 unless the Dems nominate a child molestor.