The Democratic presidential primary is over. Joe Biden is the presumptive nominee heading into the fall. And this week, Bernie Sanders and Elizabeth Warren endorsed their former competitor.On the left, the question is: What went wrong? How did Sanders lose to Biden? Why didn’t Warren catch fire? But too few of these postmortems have had sufficient data to build out their theories. And too many of them explain away strategic and tactical failures as media or establishment conspiracies.Sean McElwee has a different perspective. McElwee is the co-founder and executive director of Data for Progress, an organization that utilizes cutting-edge polling and data-analysis techniques to support progressive causes. His aim is to fashion an agenda that is both progressive and popular. But he also sits atop mountains of data that let him test hypotheses with a lot more rigor than most armchair pundits.As a result, McElwee has a fascinating, heterodox view of the 2020 primary, the Sanders and Warren campaigns, and what it will take for progressives to build power. We discuss the critical mistakes both major progressive candidates made, which progressive ideas are most popular with the American people, how the left’s theory of class politics interferes with its most obvious path to electoral victory, why maximalist policy agendas fail even when they look like they’re succeeding, what good (and bad) Overton Window politics look like, how progressives can shape Biden’s presidency, and much, much more.References: How Joe Biden won over Bernie Sanders — and the Democratic Party by Ezra KleinBook Recommendations: Deep Roots: How Slavery Still Shapes Southern Politics by Maya Sen

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