From the other side of the Atlantic, the British left watches the Democrat 2020 primary field take shape with a sense of déjà vu. The impossible has been done. On health care, climate change, and inequality, the protest fantasies of yesterday are, we are assured, the party dogmas of now. Centrists no longer get to tell the Left what’s popular and what isn’t. “Capitalist realism” — if not broken — is at least looking a bit scuffed and shopworn.

When Bernie Sanders launched his first presidential campaign in 2015, no one thought it would achieve such change in the language of the Democratic Party and in American politics. But now, in the calm of decision — and with a second Trump administration at stake — progressives are wavering about whether it’s time for “Sandersism without Sanders.” Time, that is, for a candidate who has absorbed Bernie’s progressive agenda, but one younger, with less of the battle damage of years of activism, less free with the “S” word, less white and male, and less needlessly antagonizing to the Clintonites in the party.

Fredric Jameson and Slavoj Žižek refer to the figure of the “vanishing mediator,” who like Mary Poppins or Alhambra in Ali Smith’s novel The Accidental, completely transforms a situation in the action of entering and then withdrawing from it. It took this cool old guy to give the Left its confidence back, but isn’t it time he accepted this function of temporary catalyst and made way for another candidate?