Not Me, Us
By 
Joe Biden is neither a liberal warrior nor a conservative Democrat like Joe Manchin. He is, instead, someone who has tracked the middle of the party throughout his career. In a context in which the party is moving left, that makes his presidency a potentially useful vehicle for the left:
Biden is not progressives’ champion: He does not push the envelope in the ways they want, and he has not endorsed their most ambitious ideas. But public opinion has been shifting leftward, and Biden’s thinking has shifted with it, creating a platform that progressives are genuinely excited about.
It’s “the most progressive platform of any Democratic nominee in the modern history of the party,” Waleed Shahid, communications director for Justice Democrats, a group famous (or infamous) for backing left-wing challengers to incumbent congressional Democrats, tells me.
They also see his approach as a triumph of sorts in changing the scope of what is acceptable to discuss in national politics. The “Overton window” came up repeatedly. The idea is that at any given time, only a certain set of ideas is deemed worthy of mainstream discussion, and where the contours of that set, or window, are located has meaningful impact on political outcomes. Ideas like Medicare-for-all, a Green New Deal, defunding the police, and wealth taxation did not win in the primary, but they did establish significant beachheads in public consciousness and contribute to an environment in which Biden’s very ambitious agenda can be seen as moderate.
Biden, says Shakir, “is not leading the Overton window movement, but he’s also not disregarding or moving against it.”
Shahid observes that “the most transformative presidents in our nation’s history — Lincoln, FDR, LBJ — were not ideologues fully aligned with the most radical movements of their time.” Instead, they at times worked with activists to move the ball forward and at other times trimmed their sails to meet the constraints of public opinion.
By the same token, a president can’t just impose an unwanted agenda on the rest of the party; actually enacting a policy program requires convincing the Joe Bidens of the party to go along. Which is why the idea that the left should just walk away if the One Indispensable Candidate doesn’t win the nomination is deeply silly.
Another interesting takeaway from this piece is that the public sees Biden as being more moderate than Clinton although he’s running on a more progressive agenda. Why this is true is a complicated question but electorally it’s bad news for Donald Trump.