Mitt Wit wouldn't even be an upper-tier candidate if not for his money and the fact New Hampshire is in his own backyard. The rise of Huckabee is a response to how unimpressive Romney and Giuliani are to the conservative base.
And, he has a Mormon problem in addition to a liberal record that makes him as unelectable as any candidate running.
It's only a problem for those who OBSSESS over Mormonism. To the NORMAL people it is no more of a problem than if he were a Presbyterian or a Lutheran.