There is a BIIIIIIG difference between “I'm not running for President, I'm running to be Senator from South Carolina,” and “I don't want to be President (remember how we pounded Lautenberg for a similar statement in NJ?), being President right now is a death trap; you know who I would really like to see running, though? Mitch Daniels.”
The latter statement is as definitive as you get. He ain't running, at least not in 2012. It isn't happening.
We will see what happens in the next few years, especially after DeMint is overwhelmingly reelected.