Well, yeah, while technically until Scalia died it was a 5-4 Republican-appointed majority, John Roberts has not acted as a Republican/Conservative appointee, and for reasons not clear has passed up TWO rulings that could have overturned Obamacare as unconstitutional.
There are limits to how radical a nominee Obama can get through Senate appoval, but it's still his call who gets appointed.
From what I'm reading republicans are already saying they won't even consider a nomination. There isn't a principled argument for doing that but I see it playing out that way. Regardless I'm sure Obama will choose a nominee.
