This Washington Post story clues us in to the GOP candidates' closing arguments:
Candidate ads clogged South Carolina television screens during local newscasts Friday, as they have all week. McCain stressed his long record of service to the nation as a Navy pilot and a senator, and said he is most ready to be commander in chief. Huckabee offered himself as a 'Christian leader' and an 'authentic conservative.' Thompson underscored his conservative credentials and his endorsement from South Carolina Citizens for Life, an antiabortion group. Romney emphasized his business credentials, which he said give him the expertise to 'turn around Washington.'
In about 12 hours, we'll know which message stuck.