Joe Biden is now leading Bernie Sanders by double digits in a new national poll, and he has African American voters to thank.

Before the South Carolina primary, Biden’s campaign was fading fast. He flopped in Iowa, New Hampshire, and Nevada, and many commentators, myself included, considered his presidential bid a flop. But then Biden won South Carolina, and overnight, he became the Sanders alternative, winning the endorsements of other moderate candidates such as Pete Buttigieg and Amy Klobuchar, along with many of their supporters.