That’s one theory, and conveniently it’s unfalsifiable. Absolutely, some whites are uncomfortable voting for blacks. How many is difficult to say, but given how razor-thin the margin is in Florida you might plausibly argue that the racism factor was decisive even if small.

Although as I recall, Barack Whatsisname did all right in Gillum’s home state.

Bernie has two good reasons to embrace this read on Gillum’s defeat, though. One is that support among black voters was a conspicuous, possibly fatal weakness for him in his 2016 primary challenge to Hillary. If in fact he’s thinking of running again he’ll need to do better with them, especially with competition in the primaries this time from black candidates.

“I think you know there are a lot of white folks out there who are not necessarily racist who felt uncomfortable for the first time in their lives about whether or not they wanted to vote for an African-American,” Sanders told The Daily Beast, referencing the close contests involving Andrew Gillum in Florida and Stacey Abrams in Georgia and that ads run against the two. “I think next time around, by the way, it will be a lot easier for them to do that.”…

“I think he’s a fantastic politician in the best sense of the word,” Sanders said of Gillum. “He stuck to his guns in terms of a progressive agenda. I think he ran a great campaign. And he had to take on some of the most blatant and ugly racism that we have seen in many, many years. And yet he came within a whisker of winning.”

The other reason Bernie likes the racism theory for Gillum’s and Abrams’s defeats is that he deeply dislikes the obvious alternative explanation. Bernie-style progressives underperformed across the country on Tuesday night, in some cases coming tantalizingly close to victory but falling short at the end in races where they were favored. No doubt some Floridians opted for DeSantis because Gillum was just a tad too far left to suit them (farther left than Obama, even), and in an election decided by a whisker everything off-putting about a candidate is decisive. How many votes did Gillum and Abrams lose for having the socialist seal of approval? More from NBC:

“Progressives have to really do some hard thinking about the shape of the movement looking at 2020 and beyond,” said progressive strategist Jonathan Tasini, adding that while the left had successes in some local races, they struggled in statewide contests.

“The failure, for example, of the Ben Jealous campaign in a very Democratic state says both that sticking a simple ‘progressive’ branding on a candidate’s campaign may sustain a small cult, but that isn’t enough to win enough elections.”…

Other losing progressives included congressional hopefuls like Randy “Ironstache” Bryce, who ran for the Wisconsin seat being vacated by retiring House Speaker Paul Ryan, and both progressive insurgents who won upset victories in primaries earlier this year against Democratic establishment-backed candidates, Kara Eastman in Nebraska and Dana Balter in New York.

Another progressive strategist told NBC that maybe the plan going forward should be to avoid battlegrounds and focus on taking over solid blue districts, where the general election is a foregone conclusion and all the action is in the Democratic primary. (That’s how Alexandria Ocasio-Cortez landed her new seat in Congress.) That’s not what Sanders wants to hear, though; the point of his 2016 campaign was that socialism allegedly can win a national election, which is why to this day Berniebros will assure you that he would have beaten Trump. In any race where a black progressive loses, the Sanders-friendly explanation thus necessarily must be that whites recoiled at the Democrats’ blackness, not at his progressivism. Never mind ol’ Whatsisface.

There is one well-known progressive who performed extremely well on Tuesday night, though. And Bernie noticed: “You look at Beto O’Rourke. Running in you know, what is generally considered to be a red state. Enormous excitement. Enormous citizen participation, young people participation. Broke the bank in terms of small contributions that he got. Came within a hair of winning in Texas.” I wrote about that last night and many others will spend the next year hashing out the same subject. Why did O’Rourke do so well, coming within 2.5 points of victory, running as a deep blue candidate in a deep red state? What was the secret ingredient to Betomania in Texas, his unapologetic progressivism or some unquantifiable personal charisma? (The same question might be asked of Bernie 2016.) The answer is important since the former can be replicated by other candidates but the latter can’t. And every time you hear a lefty call for Beto to run for president, you’re hearing them hedge their bets a little about that answer. They’d probably tell you if you asked that of course it was his unvarnished leftism that proved so appealing to voters — but, er, just in case it wasn’t, he should go ahead and try to win the presidency himself rather than let them some duller progressive take a shot instead.

Exit question: Was the secret ingredient to Betomania perhaps as banal as the fact that a lot of Texans aren’t wild about Ted Cruz? He’s not known for his overwhelming charm, you know, and his years as a right-wing populist antagonist in the Senate gave Democratic voters extra incentive to beat him. How would Beto have fared against Greg Abbott, say?