I think the 22nd would also preclude zombie TR who served over 7 years
I don't expect any rising of the dead, either.
That I bring up Theodore Roosevelt, the second-strongest peacetime President ever, says much about Obama. I could also bring up Eisenhower for at least one comparison (getting a truce in Korea, making a dignified exit from Iraq) as arguably the third-strongest peacetime President to date. (Unlike most historians, and I am only an amateur, I do not consider Truman a peacetime President due to the Korean War). If one is going to be a President in peacetime, a composite of Theodore Roosevelt (major reformer) and Dwight Eisenhower (make no egregious errors) is the one to aspire to. Jefferson is out of reach, as no equivalent of the Louisiana Purchase is now available, and there are no big nasty wars to evade.
Huckabee has arguably the highest floor against Obama because he can hold onto the Clinton-but-not-Obama states while holding onto Georgia and South Carolina and perhaps picking off North Carolina. He also has a lower ceiling because he has no Northern affinities. Problem is, he released an eventual cop-killer.