Foolmewunz
Grammar Resistance Leader, TLA Dictator
I can't really comment unless you name certain members. I think that Harry Reid is a good role model for obstructionism, although he's not a Republican, currently.
And you're actually hard-pressed to think of a name, a single name, of a GOP leader who's perhaps been, let's say, somewhat obstructionist in Obama's second term. I know I've wracked my brain for one and I'm just having trouble coming up with a single name. (I get my news at Fox, obviously.)