WASHINGTON Barely two hours after mixing up Volodymyr Zelenskyy and Vladimir Putin in public remarks, President Joe Biden mixed up his own vice president, Kamala Harris , with his coup-attempting predecessor, Donald Trump at a high-stakes news conference Thursday evening a gaffe likely to exacerbate concerns about his ability to beat Trump in November.

In the very first question he was asked about his confidence in Harris, Biden said: I wouldnt have picked Vice President Trump to be vice president if I didnt think she was not qualified to be president.

At a closing event of the NATO summit earlier, Biden had mistakenly referred to Ukrainian President Zelenskyy as Russias President Putin before quickly correcting himself.

Democrats uneasy about Bidens disastrous performance at his June 27 debate against Trump and looking for a solid showing at an extended news conference likely were not reassured.

Although he looked healthier and sounded sharper and more confident than he did at his debate, Biden went on to suffer several smaller verbal stumbles. He told reporters gathered at the Walter E. Washington Convention Center that he follows the advice of his commander in chief before correcting himself to say chief of staff. Referring to the June jobs report released week, he said he just created 2,000 jobs when he meant 200,000.

Later, he acknowledged he should probably modify his work schedule so that he is no longer starting his day at 7 a.m. and working past midnight. Ive just got to pace myself a little more, he said.