It certainly won't be Huntsman! Seems the former candidate for president is pretty disillusioned with the Republican Party. He kind of summed it up for me, too, with remarks made in February:
"Gone are the days when the Republican Party used to put forward big, bold, visionary stuff. I think we're going to have problems politically until we get some sort of third-party movement or some alternative voice out there that can put forward new ideas."
Huntsman has been extremely lukewarm in his endorsements of Romney, and evidently will not be campaigning for him. Don't blame you a bit, John!