Republicans are domestic right-wing terrorists. They are oppositional. If liberals like it, they hate it. If Obama is for it, they are against it. Compromising is letting Obama win, even if the compromise gives them everything they want. Participating grants Obama legitimacy, and that's something they aren't willing to do.

Thinking back about the last four years, it is worth nothing that if Republicans actually had any interest in policy they would have joined in the TipnRonniehaveadrink fantasy and joined with the Obama compromise machine. Probably best that they didn't, really, but the lesson is that... they mostly aren't interested in policy. And they certainly don't care about the deficit.