"Watch me. Mr. President, watch me. Look at us both."

“His campaign has called you ‘diminished.’ And, I’m curious how you’d respond to that,” Muir said, pressing Biden on President Donald Trump’s repeated attacks on his mental fitness.

“Watch me. Mr. President, watch me. Look at us both. Look at us both, what we say, what we do, what we control, what we know, what kind of shape we’re in,” Biden said, referring to his vice presidential pick, Sen. Kamala Harris, D-Calif.

“I think it’s a legitimate question to ask anybody over 70 years old whether or not they’re fit and whether they’re ready. But I just, only thing I can say to the American people, it’s a legitimate question to ask anybody. Watch me,” Biden told Muir during a joint interview with Harris in Wilmington, Delaware.