A doctor who served former President Obama for more than 20 years before his presidency said this week he thought former Vice President Joe Biden "looked frail" during the first Democratic debate in Miami, when he was attacked by Sen. Kamala Harris.

Dr. David Scheiner told the Washington Examiner that Biden's appearance during the debate made him nervous.

"Harris started attacking him and he looked frail to me," Scheiner said. "I sort of got the feeling he wasn’t very strong. It was similar to the feeling I got when Republicans started attacking Mueller so fiercely."

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"Harris started attacking him and he looked frail to me. I sort of got the feeling he wasn’t very strong. It was similar to the feeling I got when Republicans started attacking Mueller so fiercely." — Dr. David Scheiner, former physician of Barack Obama

Scheiner, who said he would support the 76-year-old Biden or any other Democratic nominee in the 2020 presidential election, told the Examiner he also has concerns about President Trump’s health.

He said Trump’s weight, diet and lack of exercise are all causes for concern. "He garbles,” the doctor said of the 73-year-old president. “That is a really critical issue. This is not trivial. [Late-night host] Seth Meyers jokes about it but it's not a joke. The guy just can't find the words. He's having difficulty."

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The Examiner interviewed Scheiner about new research from the American Federation for Aging Research that found all of the major candidates would likely survive at least one term in office.

Meanwhile, Biden, who was widely panned in his first debate performance, said he won’t be as “polite” in the second debate next week in Detroit.