Donald Trump. As he said, "I'm a deal guy."
I should note that while Ted Cruz, Marco Rubio, Ben Carson, and Carly Fiorina have promised to tear up the deal on "day one," Chris Christie, John Kasich, and Rand Paul have clearly said that they wouldn't, and Jeb Bush has been noncommittal. So there is a diversity of views within the party on this one. I just find it striking that while Trump sometimes comes across as completely crazy there are issues on which he makes much more sense than "establishment" politicians like Rubio.