Erick Erickson tells us why Mike Huckabee is a threat to the Republican Party's coalition than Rudy Giuliani:

The leaders of the social conservative movement who were present, the Arlington Group members you hear so much about, were ready and willing to get on board Romney's campaign on Saturday morning. Then Huckabee spoke. Then the straw vote was tabulated. Then they realized that were they to do so, it would put them completely out of step with their members.

The social conservatives do not want to rally around Huckabee because he is as distasteful to fiscalcons as Rudy is to socons. Even Tony Perkins, the head of FRC, said he hoped the social conservative candidate would be palatable to the fiscal conservatives out there. Huckabee is not.
[...]
The fiscal guys see the writing on the wall. They see Hillary's position. And they are just about ready to cut a deal. And then you have the Republican libertarians who are just about ready to really vote for Ron Paul, doing to the GOP in 2008 what Ralph Nader voters did for the Democrats in 2000.

Huckabee breaks the coalition more than Giuliani because the socons fear Hillary more than the fiscalcons do. And that is why we won't see too many of the socon leaders rallying to the clear favorite of the socon base.

That last paragraph kind of sums up a conversation my mom (a Fred Thompson supporter and social conservative) and I (a fiscal conservative) had over dinner on Friday night. I despise Hillary Clinton. I believe her goal is take more individual liberty away and dramatically increase the size of government...but isn't that what George W. Bush has done in two terms? My point to her was that the American voter, specifically a moderate and or an independent, is not going to be swayed by the anti-Hillary Clinton rhetoric because I don't believe they can look at George Bush and say, "this woman is going to be so much worse."

[UPDATE] I've cross posted this at The Liberty Papers. Ironically, the post before this one over at TLP shows the results of a recent Zogby poll of who voters would never vote for. Damn you, Doug Mataconis!!!