NORTH CHARLESTON, S.C. (AP) — Joe Biden has won the endorsement of Rep. Jim Clyburn, the highest-ranking black member of Congress and the kingmaker of South Carolina’s Democratic political orbit. The House majority whip’s backing could provide a much-needed boost for the Democratic presidential candidate before South Carolina’s primary on Saturday. Clyburn says he can think of no one “more committed to the fundamental principles that make this country what it is” than his “good friend” Biden. Biden appeared with Clyburn on Wednesday in North Charleston and thanked him. The former vice president notes Clyburn’s role in securing the Democratic votes for the 2010 health insurance overhaul that ranks as President Barack Obama’s signature domestic achievement.