“Bernie Sanders was seriously thinking about challenging our first African-American president in a primary,” says the narrator in the spot below, not very subtly for an ad aimed at a state where more than half of the electorate four years ago was black.

The inspiration for the ad is an Atlantic piece published five days ago alleging that Bernie came thisclose to jumping into the 2012 race and primarying Obama. (I wrote about the story here.) Bernie’s deputy campaign manager adamantly denied that today but Obama veterans David Plouffe and Jim Messina both confirmed it to the Atlantic on the record. Supposedly it took not one but two talkings-to by Harry Reid to convince Sanders that a primary would be futile and would risk spoiling Obama’s chances at reelection by dividing the party.

Imagine an alternate history in which Reid failed to convince him. Bernie runs, succeeds in turning a small but meaningful share of progressives bitterly against Obama, and O ends up losing the general election when those people stay home in protest. There’s no Trump era; President Romney is the GOP nominee in 2016, of course. Or imagine Obama goes on to defeat Romney in 2012 despite Bernie’s insurrection but some Democratic voters hold a grudge against him for trying to sabotage O. They later punish him by sending him down to a landslide defeat against Hillary in 2016 instead of the close-ish race we ended up with. A discouraged Sanders might not bother to run this year at all, fearing that too many rank-and-file Dems resent him to make his candidacy viable. Or possibly he runs anyway but ends up as an also-ran, with progressives concluding that two failed campaigns in the past means Bernie can’t win and they’re better off backing Elizabeth Warren.

We may have the Trump/Sanders era only because Harry farking Reid couldn’t mind his own business.

Anyway. Watch, then read on for potentially big polling news:

The last four polls of South Carolina published prior to this afternoon had Biden ahead but the race agonizingly close. As late as January 8, Joe led the state by an average of nearly 19 points. As recently as February 12, he still led by double digits. But Berniementum in New Hampshire changed the game, shrinking Biden’s lead: Of the four most recent surveys, two had him ahead by five points, one had him ahead by two points, and the last had the race … tied. A new one dropped today, right in line with the rest:

That poll was conducted during a period both before and after the most recent debate. Ominously for Biden, his polling got worse afterward:

And that was *before* Bernie’s huge win in Nevada. Sanders must be leading in South Carolina by now and ready for the knockout punch on Saturday, right?

Well, wait. There’s a second new poll out today from lefty pollster PPP, this one conducted on Sunday and earlier today, when the results in Nevada were known. Is Joe collapsing? Nope. To the contrary:

PPP’s newest poll of Democratic primary voters in South Carolina finds it looking like a two person race, with only Joe Biden and Bernie Sanders reaching double digits in their support. Biden gets 36% to 21% for Sanders, with Elizabeth Warren at 8%, Pete Buttigieg and Tom Steyer at 7%, Tulsi Gabbard at 6%, and Amy Klobuchar at 3% rounding out the field.

Other recent polls have found Steyer’s support in the 15-20% range. If he has indeed collapsed, as our poll seems to suggest, it appears his former supporters are making their way to Biden and helping him to open a bigger lead in the state. The key to Biden’s success continues to be strong support from African Americans- he gets 50% to 21% for Sanders, with no one else polling above 6%.

A 15-point lead for Biden is in line with how he was polling a month ago, when he was still the frontrunner by universal acclaim. Er, what’s going on? Two possibilities: (1) This poll is a weird outlier or (2) as noted in the excerpt, Steyer’s support has begun to crater — which wouldn’t be far-fetched. Steyer performed dismally in Nevada on Saturday, finishing with 4.7 percent of the vote despite having spent $16 million on ads there, more than any other candidate. He’s also competed aggressively in South Carolina, notching double digits in every poll taken there since New Year’s until PPP’s survey today. Maybe there’s a cohort of “Steyer-curious” voters in SC who were watching Nevada for a clue as to how viable he is. If he had done well there, it might have cemented his support in South Carolina. Because he did miserably, some chunk of Steyer voters are headed for the lifeboats and Biden.

Or maybe there’s a simpler explanation. The Steyer cohort may be fundamentally anti-Bernie and somewhat less fundamentally anti-Biden and the results in Nevada may have thrown a scare into them about the likelihood of a Sanders nomination. So now they’re voting strategically, ditching Steyer for a guy in Biden who’s somewhat more likely to blunt Bernie’s momentum on Super Tuesday. This tidbit from Nate Silver is interesting too:

Maybe some black voters were functionally undecided but had a mild preference for Steyer until recently. PPP might be picking up a late break towards Joe that other pollsters just haven’t caught yet.

And if they are, that’s pretty much the only way Super Tuesday might get a *little* interesting. If Bernie wins South Carolina, Joe’s done. If Bernie loses South Carolina narrowly, I don’t think it does much of anything to change his momentum. But if Biden wins by the sort of impressively large margin that Sanders just pulled in Nevada, the shock and massive media hype about a Biden comeback might be meaningful in the Super Tuesday states. Hype is key here — because Biden doesn’t have the dough to advertise in those states, he needs to compensate with lots of flattering media coverage. And the only way he gets that is either with a surprisingly large margin on Saturday or a bravura debate performance tomorrow night. And that second one ain’t happening, needless to say. This is Joe Biden we’re talking about.