(CNN)Everyone seems to have a strong opinion about why Hillary Clinton lost.
Bill Clinton's pollster doesn't think much of the race Hillary Clinton ran
Clinton herself -- as explained in her new memoir "What Happened" -- puts blame on her campaign, the news media, former FBI director James Comey and WikiLeaks. Donald Trump tweeted this morning that "Crooked Hillary" was simply a "bad candidate."
And now Stan Greenberg, the man who served as the lead pollster for Bill Clinton's 1992 presidential campaign (and Al Gore's 2000 campaign) has written a long essay titled "How She Lost" that slams Clinton (and her campaign) for a series of messaging, tactical and broader strategic errors.
"For me, the most glaring examples include the Clinton campaign's over-dependence on technical analytics; its failure to run campaigns to win the battleground states; the decision to focus on the rainbow base and identity politics at the expense of the working class; and the failure to address the candidate's growing 'trust problem,' to learn from events and reposition."
There's a lot to unpack there. And it's worth noting that a decent chunk of Greenberg's essay is a sort of "I tried to warn them" plea -- noting that he repeatedly told Clinton, campaign chairman John Podesta and campaign manager Robby Mook that their message wasn't working. (And he was right.)
But Greenberg's most intriguing -- and I think, important -- point is his suggestion that Clinton chose to focus on gender and race issues over class ones, and that it cost her dearly.
He writes: "Despite overwhelming evidence that the Democratic base wasn't consolidated or excited, the campaign believed Trump's tasteless attacks and Clinton's identification with every group in the rainbow coalition would produce near-universal support."
Then, later in the essay:
"The progressive debate must now address: What is the role of the working class and white working class? How do you build off of anger toward an economy that fails the middle class, but still align with professionals, innovators, and metropolitan areas? How do you credibly battle corporate influence and corrupted politics? Can you simultaneously advance identity and class politics?"
In the wake of Clinton's loss, the lesson most aspiring Democrats appear to have learned is that the way to win is to fully embrace the race and gender politics of the party's activist base -- and to move as far to the left as possible.
In short: The prevailing wisdom among 2020 Democratic aspirants is that Clinton's loss was the result of insufficient embrace of identity politics.
But Greenberg's argument is the exact opposite. That in deciding to air a "breakthrough ad in Nevada in which she hugged a Dreamer" rather than an ad with "an autoworker's daughter," Clinton was sending a message to white working-class voters that she didn't care about them.
"They were explicitly privileging race and gender over class," Greenberg writes. "And they championed policies that expanded opportunity in the way advanced by Obama."
It's not clear to me whether Greenberg's thesis will get a real test come 2020. The lone top-tier candidate who would likely run on a class message and with a class (over race and gender) focus is former Vice President Joe Biden, who remains undecided on whether he'll hop into the race.
"What happened was that this was the first campaign that I can recall where my party did not talk about what it always stood for -- and that was how to maintain a burgeoning middle class," Biden said of Clinton's failed campaign back in March. "You didn't hear a single solitary sentence in the last campaign about that guy working on the assembly line making $60,000 bucks a year and a wife making $32,000 as a hostess in restaurant."
If Biden doesn't run, there's no obvious candidate to fill that role -- although it's worth noting that Bernie Sanders does talk a lot about class. (Sanders' focus on class over race and/or gender politics was roundly criticized by Clinton and her allies during the 2016 primary campaign.)
Dismiss Greenberg's criticism if you will. But he has been a major figure in Democratic politics for a very long time -- and his diagnosis of what went wrong for Clinton is well worth the read.