It isn't necessarily about making backroom deals. The tribe mentality is so deep that I'm not sure that Sanders and McConnell would recognize that the other person is trying to do what they think is best for the country. I'm not sure they could sit down and talk about their families or their favorite place to travel.
I just think the tribe mentality got informed by the constant news cycle now. A lot of sane people have probably left congress and now you have a lot of hyperpartisans who like fighting for its own sake.
