Former Republican vice presidential candidate has yet to get in the race, but Sen. John McCain (R-AZ) said Sunday that his former running mate would be tough to beat.

"Karl Rove said just this morning that he'd put money on Sarah Palin running," CBS' Norah O'Donnell told McCain. "Do you think Sarah Palin will run?"

"I do not know," McCain replied. "I certainly put some credence to Karl Rove. After all, he is one of the guys that beat me... That's a decision that is so personal, got to do with your family. It's got to do with all of these things. It's hard for me to know if Sarah should run or not. I think she would be very formidable."

Weighing in on the other candidates, McCain refused criticize Gov. Rick Perry's stance on climate change or his suggestion that Fed Chairman Ben Bernanke was guilty of treason.

"I don't expect to agree with every candidate on every issue," the senator explained. "These are the things you go through. This is why campaigns are tough."