The same conventional wisdom that was wrong about everything else suggested that when Barack Obama left New Hampshire with two early victories in his pocket, African-Americans in South Carolina would start believing he could win and then swing hard in his direction.

It hasn't exactly happened that way, of course, and organizers for both Obama and Hillary Clinton remain locked in what the Associated Press calls "fierce combat for the support of black voters" in South Carolina.

What could tip the balance? Just a day ago, the mainstream media was dismissing -- probably fairly -- the practical effect of John Kerry's endorsement of Obama. But today, the New York Times says the prospect of an endorsement from South Carolina Rep. James Clyburn -- the highest-ranking African-American in Congress -- "could carry significant last-minute weight given his standing among African-Americans and his deep political connections throughout the state, as well as the role he played in winning the right for South Carolina to have the showdown."

Would a Clyburn endorsement really mean that much? Maybe, but the "why" here is probably more important than the "who." As the Times notes, Clyburn is rethinking his "neutral stance" in the race out of "disappointment at comments by Bill and Hillary Rodham Clinton that he saw as diminishing the historic role of civil rights activists."

At the heart of the matter, apparently: Clyburn's view that Hillary Clinton denigrated the work of the civil rights movement Monday when she tried to emphasize the importance of electing an experienced president.

What Clinton said: "I would point to the fact that that Dr. King's dream began to be realized when President Johnson passed the Civil Rights Act of 1964, when he was able to get through Congress something that President Kennedy was hopeful to do, the President before had not even tried, but it took a president to get it done. That dream became a reality, the power of that dream became real in people's lives because we had a president who said, 'We are going to do it,' and actually got it accomplished."