Anderson Cooper tried to corner Vice President Kamala Harris into criticizing Joe Biden's performance in last night's debate.

"You debated against then Vice President Biden four years ago, and he was a very different person on the stage four years ago when you debated him. That's certainly true, is it not?" he prodded.

"Anderson, the point has to be performance in terms of what a president does. A president who incites an insurrection against the Capitol," she said.

"But I got the point that you're making about a one and a half hour debate tonight. I'm talking about three and a half years of performance in work that has been historic, whether it be infrastructure."

"But is that the man, the man who we saw on the stage tonight, is that the other guy on the debate stage?" Cooper said.

"The person that you saw on the debate stage that has for the last three and a half years, up until today, performed in a way that has been about whether it be in the Oval Office, negotiating bipartisan deals so that we have an infrastructure, a real infrastructure plan where we're putting trillions of dollars on the streets of America to upgrade our infrastructure," she replied.

"Whether it be the person I see in the Oval Office who is meeting with heads of the military and the intelligence community and in the Situation Room, ensuring the safety of America.

"The person I see is Joe Biden on the world stage, convening world leaders who often ask for his advice, most recently just during the G7 conference.

"So I'm not going to spend all night with you talking about the last 90 minutes when I've been watching the last three and a half years of performance."

Well, she's right. He's been an extraordinarily effective president. But there's no question that Biden had a bad night, and it was kind of scary. As in, WTF?

But are we really talking about booting him off the ticket because he had a bad night? (I remember Obama's horrible performance debating Mitt Romney, and how Democrats were wringing their hands then.)

We'll learn more in the next few weeks that will either confirm our fears -- or reassure us. Here's Biden at a post-debate event: