Romney hasn't campaigned against the President yet. Once he has the nomination sown up, it'll be interesting to see how things change.
Right now, I expect the race to be close until the last week or 2 and then 1 of them will pull away. Unless the President can change the answer to the question Reagan asked the American people: 'are you better off today than you were 4 years ago,' then he'll be a 1 and done. If the economy is coming around or if something major breaks his way, then he might be able to have that question break his way; right now, it's not there.