There are two GOP constituents that Huckabee seems to be alienating. The Catholic vote and the Mormon vote. Huck's speaking at the anti-Catholic Cornerstone Baptist Church has apparently angered a lot of Catholics, fanning flames of distrust that have been there for, well, a long time. I've noted several places I'd prefer John McCain over Mitt Romney but would still be okay with Romney as the GOP nominee, and Huck's sly whisper campaign may have worked in Iowa, but it could mean trouble if he actually gets the Republican nominee.
Huck was the keynote speaker at an anti-Mormon rally held by the SBC in 1998. But in 2007 he claims he doesn't know much about them, then coyly asks "Don't they believe Jesus and Satan are brothers?" He's tap-danced every time he's been asked the question if Mormons are Christians, because the SBC would vehemently say No if he said Yes.
When you look at how close elections can get, and how red states like Arizona, New Mexico, and Nevada are looking more purple, add to that Huck as the GOP representative. I think a vast chunk of LDS Republicans would rather vote for Barack Obama than a Baptist preacher they think believes they're all going to burn in hell forever. It could be enough to turn Utah and Idaho blue, and that would sure change the political paradigm forever.
I watched Chris Matthews' jaw clench when the religious test came up between Huckabee and Romney. A Catholic, Matthews was clearly upset that 48 years after JFK's speech, we still live in a climate where Romney's faith speech from last month was believed necessary.