Despite Joe Biden’s victory in the 2020 presidential election and the Democrats’ razor-thin margin of control over the US Senate, the party’s underwhelming showing in down-ballot races — both at the federal and state levels — has put it on course for an internal reckoning. What lessons will the Democrats learn from their losses in the House, their near-failure to capture the working Senate majority required to pass any meaningful progressive legislation over the next two years, and their forfeiture of multiple state legislative chambers leading up to a crucial redistricting year? And what are the implications of the Democrats’ internal postmortem for progressive electoral politics? While not written to anticipate the contours of post-2020 Democratic politics, Seth Masket’s masterful Learning From Loss: The Democrats, 2016–2020 provides a wealth of useful insights for understanding the Democrats’ likely trajectory over the coming years, as well as the strategic decisions progressives must grapple with as they seek to expand their influence on Democratic Party politics.

First, Learning From Loss makes a forceful case that the Democratic Party is both better organized and, paradoxically, more porous than most commentators on the progressive left allow. In particular, Masket argues that Biden’s victory in the 2020 Democratic presidential primary had much less to do with a concerted effort by Democratic leaders to tip the scales against progressives, and much more to do with a hyperfocus on electability among the party’s base, combined with a powerful (if empirically questionable) assumption that progressive presidential candidates are simply not electable. These findings should cast serious doubt on claims that progressives are structurally incapable of wielding influence within, or even taking control of, the Democratic Party, even as the medium-term prospects of doing so appear weaker in light of the 2020 election results.

Next, Masket makes a series of important contributions to understanding the legacy and potential future of the Bernie Sanders wing of the Democratic Party. Through a detailed analysis of Democratic donor patterns and candidate staff reshuffling between 2016 and 2020, he shows that, although the democratic socialist faction of the party was unable to expand its 2016 ranks significantly in 2020, it has become a distinct and stable force within the party that is not likely to dissipate in the near future. At the same time, however, Masket’s findings suggest that there is no obvious path forward for Sanders’s coalition to meaningfully expand its ranks within the party over the coming years (at least not outside of heavily progressive areas of the country). This poses a major challenge to democratic socialists in Congress and in state legislatures who have experienced impressive gains in recent years (including in 2020) but who appear to be edging ever closer to a relatively low electoral ceiling.