The left has a fever and the only prescription is Guy Who Just Lost His Senate Race.

The most popular potential candidate was [Beto] O’Rourke, D-Texas, who was selected by 15.6 percent of respondents, followed by [Joe] Biden at 14.9 percent, and then Sen. Bernie Sanders, I-Vt., with 13.1 percent.

It’s another sign of O’Rourke’s surprising popularity among national Democrats and a potentially troubling indication for Sanders, whom MoveOn endorsed in the 2016 Democratic primary. That year, 78 percent of MoveOn members voted to back Sanders over Hillary Clinton

The three men were followed by Sen. Kamala Harris, D-Calif., who garnered 10 percent support, and Sen. Elizabeth Warren, D-Mass., with 6.4 percent. Meanwhile, three Democratic senators, Sherrod Brown of Ohio, Amy Klobuchar of Minnesota and Cory Booker of New Jersey, and former New York City Mayor Michael Bloomberg were each selected by about 3 percent of members.

I don’t know the demographics of MoveOn’s members offhand but it’s a progressive activist group so they presumably tilt further left than the Democratic Party as a whole. The results here don’t lead to the conclusion that O’Rourke is now the overall frontrunner for the nomination, in other words. But they’re interesting as a window onto the primary-within-a-primary, to see which candidate might emerge a la Bernie 2016 as the left’s favorite choice. This is a good result for O’Rourke, of course, but also for Uncle Joe Biden, who outpolls even Bernie himself as a leftist favorite. Normally I’d chalk that up to name recognition but MoveOn members are politically active and therefore probably more familiar with lesser-known candidates than the average Democrat is. (Look no further than the fact that a congressman leads here.) Biden may be the closest thing the party has to a consensus choice that pleases both liberals and centrists.

It’s a bad poll for Bernie for obvious reasons but also for Elizabeth Warren, who continues to underperform in early surveys of the race. MoveOn-types should regard her warmly; as it is, she’s pulling less than half of Biden’s or Sanders’s take and trails newbie Kamala Harris. If she’s not top-tier here, where is she top-tier? Is New Hampshire going to deliver for her just because she lives next door?

Oh, by the way: The signs continue to pile up that O’Rourke really is going to jump in. On top of having met recently with Barack Obama, he phoned (dry heave) Al Sharpton and recently spoke to the almost-but-not-quite governor-elect of Florida, Andrew Gillum. Although, interestingly, it was the latter who initiated the call to O’Rourke, not vice versa:

The phone call with Gillum has not been previously reported, and was described to NBC News by two sources told of it later. One source, granted anonymity to describe a private conversation, said the pair discussed their mutual preference that someone “young and unapologetically progressive” lead the Democratic Party going forward. The two men had never spoken before, according to the source, and it was Gillum who reached out to O’Rourke to arrange the call.

Gillum is also considering running for president. In some ways he’s in the same boat as O’Rourke — both young, both overnight stars in their party, both recently having fallen just short of winning statewide office in a populous state. It’s Beto who has the buzz, though, and Beto who proved to be the sort of fundraising juggernaut that might make him competitive in a national primary. I’d be curious to know if Gillum reached out hoping to win his endorsement in case O’Rourke doesn’t run or if he reached out to kinda sorta offer his endorsement in case Gillum himself doesn’t run.

The reason O’Rourke is touching base with Sharpton is because he’s internalized a hard lesson for Bernie fans from the 2016 primaries. No matter how strong your progressive cred, no matter how much populist buzz you enjoy, even a lackluster establishmentarian can beat you if he or she is popular among black voters. NBC sums it up: “Clinton’s final 361-pledged delegate lead over Sanders can be traced directly to lopsided victories in the 14 jurisdictions with the highest black populations.” And Beto 2020 would face challenges that Bernie 2016 didn’t — fierce competition for the progressive base, a primary calendar with a variety of southern states that have large black minorities voting early-ish, and two formidable black opponents in Kamala Harris and Cory Booker. Harris has a potent extra advantage as well by virtue of the fact that her home state of California will hold its primary early in 2020, with voting by mail to begin right around the time of the Iowa caucuses. And unlike Hillary, Harris is no centrist. She can pull progressive votes from O’Rourke more easily than Clinton could from Sanders.

Bottom line: Whoever’s serious about running had better get to work early on winning over black voters. It’s an open question whether Harris and/or Booker will clean up among African-American Democrats; Obama did in 2008 but that was effectively a two-person primary and his candidacy was historic. Where will that group go in a 15-person primary with multiple black candidates in the field plus some white ones who are lining up warm words from people as influential as Obama and Sharpton? O’Rourke and other white candidates don’t need endorsements per se from black leaders (although of course they’d like them) but they do want some signal that it’s okay to prefer a white candidate as nominee to Harris or Booker, that racial solidarity doesn’t compel a vote for either of the latter. Obama would support that sentiment, for sure. (He probably won’t endorse anyone in the primary but he certainly won’t endorse someone other than Biden if Uncle Joe runs.) Sharpton? Eh. Don’t forget, though, that O’Rourke earned some applause from black celebrities like LeBron James and Beyonce during his Senate campaign, partly for defending the rights of NFL players to protest police brutality by kneeling during the anthem. Watching how the black vote splits will be one of the most fascinating subplots of the Democratic primary.

Exit question from Politico: Should Joe Biden, errrrrrrrr, run as an independent candidate with Mitt Romney as his VP? I’m sure he’d pile up Democratic votes by … quitting the party that twice nominated him from VP and choosing a Republican as his running mate at a moment when liberals are drifting further left. What good progressive wouldn’t support installing the oldest president in American history with someone from the other party a heartbeat away?