Joe Biden has the Democratic nomination nearly locked up. Progressives are sorely disappointed, and it’s easy to sympathize. Mr. Biden is an old hand of the party’s old guard, cozy with big finance and spellbound by a bygone era of bipartisan amity. A man in denial about the depth of polarization and systemic corruption can’t begin to fix what’s wrong with the country or the Democratic Party.

Progressives need to understand that Bernie Sanders was never the answer. Support for “democratic socialism” may be on the rise, but it’s not nearly enough to underwrite a governing majority. Jitters about electability aren’t the only thing doing Mr. Sanders in, though.

Democrats are hungry for reform, not revolution. To oust Mr. Trump and especially to govern effectively, Democrats need a fighting creed that avoids both Mr. Biden’s blinkered complacency and Mr. Sanders’s quixotic hand-waving. She may be gone from the race, but Elizabeth Warren has a plan for that. Democrats should pick up the fallen flag of Warren-ism and run.

America is embroiled in a crisis of deepening corruption. A self-reinforcing spiral of regulatory capture, self-dealing and influence-peddling has led to intensely concentrated power that is at once economic and political. That concentrated power has rigged the rules that define the structure of America’s democracy and economy to the advantage of the powerful at the expense of ordinary Americans. This has deprived us of our most vital means of collective self-defense: meaningful democratic control over the institutions that shape our lives. Unless we fight to unrig the system, millions of us will continue to live and die on the terms of unaccountable power.