Inside the Democratic Party, Bloomberg’s ascent would put a sharp brake on the two major post-Obama trends in liberalism: The Great Awokening on race and sex and culture, and the turn against technocracy in economic policymaking.

Yes, Bloomberg has adapted his policy views to better fit the current liberal consensus, and his views on social issues were liberal to begin with. But he has the record of a deficit and foreign policy hawk, the soul of a Wall Street centrist, and a history of racial and religious profiling and sexist misbehavior. More than any other contender, his nomination would pull the party back toward where it stood before the rise of Bernie Sanders and Black Lives Matter and #MeToo, and root liberalism once more in professional-class interests and a Washington-Wall Street mindmeld.

These are good reasons to assume that he cannot be the nominee, and excellent reasons for social progressives and socialists alike to want to beat him. The only way they will fail is if Bloomberg succeeds in casting himself as the unusual answer to an unusual incumbent — combining the Democratic fear of a Trump second term, his own reputation for effective management and the promise of spending his fortune to crush Trump into a more compelling electability pitch than the race’s other moderates.

But Democrats considering this sales pitch should be very clear on what a Bloomberg presidency would mean. Bloomberg does not have Trump’s flagrant vices (though some of his alleged behavior with women is pretty bad) or his bald disdain for norms and rules and legal niceties, and so a Bloomberg presidency will feel less institutionally threatening, less constitutionally perilous, than the ongoing wildness of the Trump era — in addition to delivering at least some of the policy changes that liberals and Democrats desire.

However, feelings can be deceiving. Trump’s authoritarian tendencies are naked on his Twitter feed, but Bloomberg’s imperial instincts, his indifference to limits on his power, are a conspicuous feature of his career. Trump jokes about running for a third term; Bloomberg actually managed it, bulldozing through the necessary legal changes. Trump tries to bully the F.B.I. and undermine civil liberties; Bloomberg ran New York as a miniature surveillance state. Trump has cowed the Republican Party with celebrity and bombast; Bloomberg has spent his political career buying organizations and politicians that might otherwise impede him. Trump blusters and bullies the press; Bloomberg literally owns a major media organization. Trump has Putin envy; Bloomberg hearts Xi Jinping.