He could definitely win the nomination. it's not a remote possibility that he wins the White House.
I'm not sure Romney has the stomach for this. After cockily running against Obama, he must now confront Gingrich. he must fight dirty, because Newt fights dirty. Mitt must exchange white gloves for boxing gloves. Or bare knuckles.
Gingrich's advantage over O. is that, despite his history, newt doesn't come on as a backer of Team Boehner. He pitches himself as a partner of Reagan and (!) Clinton. Obama would also have to take on Gingrich himself and we all know how the Newtster handles that. With venomous anger. O. will not be able stay cool. The best way to fight Gingrich is with undeniable facts. Trouble is, newt will deny them.