What We Learned From Biden’s Big Night at the D.N.C.

“You can think of this sort of like “Survivor” on all of the people who have also ran,” Mr. Booker said. (Before moderating the tributes and recollections for Mr. Biden, Mr. Booker had a question for Mr. Sanders: “Why does my girlfriend like you more than me?”)

Pete Buttigieg recalled a time when Mr. Biden learned that his rival had hired someone he knew. The former vice president pulled Mr. Buttigieg aside and “let me know that that was someone who had gone through a family tragedy and just thought it was important for me to know that, as someone who is working for me.”

Senator Amy Klobuchar recalled delivering a speech to a largely empty Senate chamber, one even her mother might not have watched on C-SPAN. Then she got a call from Mr. Biden, who wanted to talk about her speech.

“That kind of goes to not only his kindness — for calling me and being a mentor — but it shows how much he cares about our government,” Ms. Klobuchar said.

Mr. Sanders interjected, wondering if Ms. Klobuchar’s mother did indeed tune into C-SPAN.

Nearly every candidate spoke more to Mr. Biden’s character than any policy platform.

“The magic of Joe Biden is, everything he does becomes the new reasonable,” Mr. Yang said.

Mr. Sanders, whose praise perhaps carries the most weight for his legion of progressive supporters, who may still be leery of supporting the more moderate Mr. Biden, reiterated his pledge of support.

“In Joe Biden, you have a human being who is empathetic, who is honest, who is decent,” he said. “And at this particular moment in American history, my God this is something that this country really needs. And all of us, whether you are progressives, moderates or conservatives, have got to come together.”