In a Beliefnet interview, Mike Huckabee elaborates on his comment that "what we need to do" is "amend the Constitution so it's in God's standards." He says he was referring specifically to amendments banning abortion and defining marriage as a union between one man and one woman:
People sometimes say we shouldn't have a human life amendment or a marriage amendment because the Constitution is far too sacred to change, and my point is, the Constitution was created as a document that could be changed. That's the genius of it. The Bible, however, was not created to be amended and altered with each passing culture. If we have a definition of marriage, that we don't change that definition, that we affirm that definition. And that the sanctity of human life is not just a religious issue. It's an issue that goes to the very heart of our civilization of all people being equal, endowed by their creator with alienable [sic] rights of life, liberty, and the pursuit of happiness. That was the point. The Bible was not written to be amended. The Constitution was….
I don't think that's a radical view to say we're going to affirm marriage. I think the radical view is to say that we're going to change the definition of marriage so that it can mean two men, two women, a man and three women, a man and a child, a man and animal. Again, once we change the definition, the door is open to change it again. I think the radical position is to make a change in what's been historic.
If "the Bible was not written to be amended," what's the New Testament all about? And if Huckabee wants to stick with the biblical definition of marriage, why does he imply that a marriage consisting of "a man and three women" is some newfangled challenge to the family arrangements endorsed by God? According to the Bible, Abraham sired one son with Hagar (his concubine) and one with Sarah (his full-fledged wife) while they were both living and had more children with Keturah after Sarah's death. Jacob had two wives (Rachel and Leah) and two concubines (Bilhah and Zilpah) at the same time, producing children with each of them. Moses apparently had two wives (Ziporrah and "the Ethiopian woman"). David and Solomon each had a bunch. (More examples here.) As far as abortion goes, the Bible (the "Old Testament" part, at least) has nothing clear to say about it one way or another. It seems Huckabee, despite his firm stance against amending the Bible, is doing exactly that, based on his own moral intuitions, and he wants to treat the Constiution in a similar manner.