It was a republican plan to begin with. As soon as Obama got on board, they couldn't even consider it. He was naive to think the republicans would actually work with their president but it was a move that would have brought some people from across the aisle together...and of course fix a terribly broken healthcare system and bring healthcare coverage to the millions and millions of the previously uninsured/unisurable.
Eh. IMO that's the good argument they have in not liking it. Romney's plan was good for the state. It falls in lines with them wanting states to have the final say in it.