Because he's managed to position himself to the left of Hillary Clinton on the question of a national smoking ban in public places.
What, so is secondhand smoke cool? No--but from a conservative, fundamental, principled point of view, Huckabee is wrong. Jim Geraghty of NRO's Campaign Spot explains why: "I don't have much of a problem with local governments mandating the creation of non-smoking sections. I know second-hand smoke is bad, that's why I avoid it. I think it ought to be up to businesses to decide whether it's permitted in their offices or other work environments. But it's not a federal issue, and a one-size-fits-all national law is statism run amok. Plus, there's something unseemly about the way smoking has become this convenient punching bag of a public health enemy in a society that otherwise is growing ever-more-tolerant on other substances."
Bingo. Huckabee has hurt himself significantly with conservative Republicans on this.