Angry Bernie voters may protest furiously that it was the “establishment” that revived Biden to seize a prize that seemed theirs. But that’s wrong. Biden’s rescuers weren’t party elders but a marginalized constituency that is often taken for granted: Southern blacks.

It was black voters who gave Biden a huge win in South Carolina on Saturday, reviving his fortunes and clarifying his role as the alternative to Sanders. It obviously helped that Pete Buttigieg and Amy Klobuchar exited the race and, along with Beto O’Rourke, endorsed Biden in time for Super Tuesday (and Klobuchar may end up Biden’s running mate, while Buttigieg could end up in a Biden cabinet). But this wasn’t a coronation; it was a groundswell among moderates fearful that a Sanders nomination would be a Republican dream.

We in the pundit world are awful at predictions, and we should all be humbled by the conventional wisdom of 2016 that Trump was unelectable. Still, Sanders is the single most liberal member of the Senate, according to GovTrack, and old-timers remember what happened to Barry Goldwater on the right and George McGovern on the left. Democratic members of the House — who presumably know something about their own districts — say that it would be harder for them to win with Sanders at the top of the ticket.

At a dinner with a dozen Democratic House members recently, I was struck by how worried some were that a Sanders nomination would cost them any chance of a Democratic Senate and might even hand the House itself back to Republicans.

I’m closer to some of Sanders’s positions than to Biden’s, and I particularly admire Sanders’s leadership and authenticity on human rights issues like Yemen. But I don’t think Sanders would be able to accomplish his aims as president any more than he has been able to as a senator (he was a primary sponsor of only seven bills that became law, and they are mostly insignificant items, such as naming post offices or designating “Vermont Bicentennial Day”).