But the Democratic Party of late has gotten into a bad habit of trying to prevent a serious succession battle. In 2000, the party was overwhelmingly united behind Vice President Al Gore; his only opponent, Sen. Bill Bradley, barely got any traction. In 2008, the party attempted to unify behind Hillary Clinton, before Barack Obama made that impossible. They largely cleared the field for Clinton in her second attempt, in 2016, leaving as her only serious opponent a Vermont socialist who nobody expected to amount to much. I don’t think it’s an accident that these efforts, aimed at avoiding conflict and preserving unity for the general election, have largely backfired, leaving them with nominees who are unprepared to fight their way to victory. Not every contested primary produces a general election winner, but all of their successful recent nominees — Jimmy Carter in 1976, Bill Clinton in 1992, Obama in 2008 — won their nominations in a fight.

Moreover, in 2024 (or 2028), the Democrats are going to need to have a fight. For most of the 2020 campaign, the bulk of the Democratic contenders vied for support from the activist left, only to have the voters choose the candidate of calm, centrist continuity. The challenges the country faces have multiplied severalfold since then, and both the opportunities and risks of governance are much higher than they were when Biden clinched the nomination. Whether we’re talking about rebuilding the economy or rethinking criminal justice or facing the twin challenges of an increasingly belligerent China and the planetary threat of climate change, the docket is astoundingly full. How can anyone blithely assume that the Biden administration will handle all of it so well that “don’t change horses in mid-stream” will unquestionably be the winning slogan for his successor?