5. Bob McDonnell - governor of Virginia. Good pol and would be difficult for President to exploit his major weakinesses: lack of experience and foreign policy
4. Bobby Jindal - governor of Louisiana. A person of color who could match wits with the President who had a record of accomplishment.
3. John Thune - Senator South Dakota. Made for tv candidate similar to Mitt Romney without the flip flops but comes with consistent conservative record and giant-killer history of defeating Senate Democratic leader Tom Daschle.
2. David Petraus - military leader. If he declared as a Republican, identified with the best of the tea party and Occupy Wall Street, while respectfully criticizing the President; he'd be tough to beat and to attack.
1. Marco Rubio - Senator Florida. His potential to excite conservative base and cut into the President's latino voter base, in addition to potentially taking Florida off the board.