After a year of stages crowded with flash-in-the-pan phenoms and forgettable faces, the race for the 2020 Democratic presidential nomination is about to yield a totally new kind of debate: Joe Biden versus Bernie Sanders, mano a mano.

That’s bad news for Biden, and his team knows it. We know they know it because they won’t accept Sanders’s offer for a one-on-one debate about health care policy; because they’re lobbying to make the debate format less demanding; because Biden is refusing invitations for extended interviews on cable news; and because he was recently spotted handing out leaflets to reporters after an event instead of talking to them directly — clearly a workaround designed by his staff to prevent him from putting his foot in his mouth.

His staff are right to be worried. The elder statesman is prone to lapses in coherence, to put it politely. The signs have been there for months: when Biden asked supporters to “go to Joe 30330 and help me in this fight” in the August debate, the Guardian called it “one of the most cryptic gaffes of his career.” But it was only the beginning.