“With all due respect to Medicare for all, you have a single-payer system in Italy,” he said. “It doesn’t work there.”
It was not clear what the public appetite might be for a debate in these times. Sunday evening was always going to be weird, eerie — a reminder, without a live audience, of how far the nation has traveled in the handful of days since its people were advised not to travel far at all.
One question centered on the candidates’ approaches to crisis hygiene.
“I’m using a lot of soap and hand sanitizers,” Mr. Sanders said.
“I make sure I don’t touch my face and so on,” Mr. Biden reported.
The forum was, if nothing else, a live event to be shared with a large audience. Gone was the viewership competition from N.B.A. games, baseball spring training, a college basketball tournament selection show.
Why not watch two septuagenarians talk for two hours?
Since taking control of the primary with commanding victories over the past two weeks, Mr. Biden has saluted Mr. Sanders’s policy instincts, to a point, mindful that he will need the senator’s supporters to join him in the fall if he is the nominee. (This did not dissuade him from a swaggering aside about his electoral success in the face of Mr. Sanders’s superior resources at the time. “I didn’t have any money, and I still won!” Mr. Biden enthused, as Mr. Sanders dinged him for being supported by the ultrarich.)
In recent days, Mr. Biden has embraced versions of plans put forth by Mr. Sanders and Senator Elizabeth Warren, whose progressive campaign for the presidency ended earlier this month, as the former vice president moves to shore up support on the left.
In one extraordinary turn on Sunday, Mr. Biden committed for the first time to having a woman as his running mate. Mr. Sanders said he would “in all likelihood” but did not go quite as far.