So practiced riffs that were somewhat pat before the pandemic were wholly pertinent, such as Biden’s recognition that while he and Sanders differ on how to improve health care or tackle other problems in America, “We don’t disagree on the principle. We fundamentally disagree with this president on everything.”

“So,” he added, “this is much bigger than whether or not I’m the nominee or Bernie’s the nominee. We must defeat Donald Trump.”

And Biden was able to portray Sanders’s grander plans for transforming the American economy as luxuries unaffordable in the face of a scourge, as distractions from the emergency upon us. “People are looking for results, not a revolution,” Biden said.

Barring some remarkable, unforeseeable development, Sunday night was likely the valediction to Sanders’s bid for the Democratic nomination. That’s not because there was any particular, glaring deficiency in Sanders’s performance, a thorough and sometimes fierce grilling of Biden that correctly identified his evasions, inconsistencies and episodes of flawed judgment.

Sanders projected passion and self-assurance. He defended himself well against Biden’s attacks. And he raised fair, even necessary questions about whether, on issues like climate change, Biden’s proposals were more timid than the stakes demanded.

But there was something strained and strange about Sanders’s repeated pivots from the pandemic to income inequality, from the pandemic to corrupt pharmaceutical executives, from the pandemic to how many millionaires and billionaires have contributed to Biden’s campaign. The world has been transformed; the script remains the same.

And he couldn’t claim the kind of experience that Biden repeatedly did, the intimate knowledge of what it’s like to be at the center of crucial national decisions.