The abortion debate is completely "W"rong.

The current debate about the origins of life doesn't concern the USA Constitution.

Huckabee can go on and on about the beginning of life all he wants, but, the US Constitution isn't interested in religious definitions.

The US Constitution is interested in citizenship. If argued correctly late term abortions are constitutional, especially when it is to save the woman's life and the well being of her family.

The US Constitution stipulates that the highest office in the land, President of the United States of American has to be occupied by "a natural born citizen."

Article II, Section 1 of the US Constitution:

No person except a natural born citizen, or a citizen of the United States, at the time of the adoption of this Constitution, shall be eligible to the office of President; 

You can argue all you want about when life begins, but, the US Constitution has no interest in a baby until it is born. While the UNBORN are still in utero, there is no debate about the beginning of the LEGAL life of a citizen. It is not until the baby is born.

Roe v Wade was decided based in oppressive state law. It was decided because the lack of a safe abortion was killing women and leaving their families without wives and mothers. Roe v Wade was always about women, not about babies. 

The woman is the citizen, not the fetus. 

There is case law, four case law decision that defines "natural born citizen. United States v. Wong Kim Ark, 169 US 649 (1898) is the most interesting.

The Venus, 12 U.S.478 Cranch 253 253 (1814)

Shanks v. Dupont, 28 U.S. 3 Pet. 242 242 (1830)

Minor v. Happersett , 88 U.S. 162 (1875)

United States v. Wong Kim Ark, 169 U.S. 649 (1898)

In this case, Wong Kim Ark, the son of 2 resident Chinese aliens, claimed U.S. Citizenship and was vindicated by the court on the basis of the 14th Amendment.  In this case the Justice Gray gave the opinion of the court.  On p. 168-9 of the record, He cites approvingly the decision in Minor vs. Happersett:

At common law, with the nomenclature of which the framers of the Constitution were familiar, it was never doubted that

all children, born in a country of parents who were its citizens, became themselves, upon their birth, citizens also. These were natives, or natural-born citizens,

as distinguished from aliens or foreigners.

On the basis of the 14th Amendment, however, the majority opinion coined a new definition for “native citizen”, as anyone who was born in the U.S.A., under the jurisdiction of the United States.  The Court gave a novel interpretation to jurisdiction, and thus extended citizenship to all born in the country (excepting those born of ambassadors and foreign armies etc.); but it did not extend the meaning of the term “natural born citizen.”

CONCLUSION

Finally it should be noted, that to define a term is to indicate the category or class of things which it signifies.  In this sense, the Supreme Court of the United States has never applied the term “natural born citizen” to any other category than “those born in the country of parents who are citizens thereof”.

Hence every U.S. Citizen must accept this definition or categorical designation, and fulfil his constitutional duties accordingly.  No member of Congress, no judge of the Federal Judiciary, no elected or appointed official in Federal or State government has the right to use any other definition; and if he does, he is acting unlawfully, because unconstitutionally.