Jon Huntsman for his previous fulsome praise of President Obama as a "remarkable leader"
(and admittedly, it would make for some awkward attack ads if he were, in fact the nominee).
Projecting an air of moral superiority and indulging in the occasional bit of sanctimonious hectoring from the debate platform likewise isn't going to win you a lot of hearts and minds.
Either Huntsman himself is the worst politician known to man, or he accepted the worst political advice known to man. Why on earth would he think he would benefit from repeatedly insulting the people whose support he needs (in a manner reminiscent of the worst of left-wing "culture"), and by underplaying the genuinely conservative parts of his record?
Perhaps he will continue to purvey the comforting fiction that it was his statesmanlike public service for a Democrat that did him in. Except that it wasn't. It was the tone of the man and the tenor of the campaign he ran.