Washington. President Joe Biden used his closely watched news conference Thursday to deliver a forceful defense of his foreign and domestic policies and batted away questions about his ability to serve another four years, declaring: “I’m not in this for my legacy. I’m in this to complete the job.”

Early on, he made one notable flub when he bobbled a reference to Vice President Kamala Harris. But for an hour, he largely held his own under intense questioning, eschewing any suggestion that he was in decline, no longer capable of leading the nation and too old to serve another term.

It was unclear whether the performance was enough to change the dynamic that has set in: A growing number of Democratic lawmakers, donors and celebrities are calling on him to step aside -- not to mention the majority of voters expressing doubts that he is up to the job -- and Biden is digging in, insisting he’s staying in the race and will win come November. And the longer the infighting continues, the less the Democrats are presenting a united front against Republican Donald Trump.

“If I slow down and I can't get the job done, that’s a sign that I shouldn’t be doing it,” Biden said. “But there’s no indication of that yet -- none.”

Yet even as he wrapped his news conference, the 81-year-old leader was confronting calls to step aside. In a statement released shortly after he walked offstage, Connecticut Rep. Jim Himes, the top Democrat on the House Intelligence Committee, said Biden should end his candidacy, considering his “remarkable legacy in American history.” Fifteen other House Democrats have called on him to make way for a new candidate.

Vintage Biden during the news conference
Biden said he was willing to take another neurological assessment before the election, but only if his doctors recommended it. His last exam was in January and the results of it were released in February.

In his first exchange with reporters, Biden was asked about losing support among many of his fellow Democrats and unionists, and was asked about Vice President Kamala Harris. Biden was at first defiant, saying the “UAW endorsed me, but go ahead,” meaning the United Auto Workers. But then he mixed up Harris and Trump, saying, “I wouldn’t have picked Vice President Trump to be vice president if she wasn’t qualified."

Trump weighed in live on Biden’s news conference with a post on his social media network of a video clip of the president saying “Vice President Trump.”

Trump added sarcastically, “Great job, Joe!”

Most of news conference was vintage Biden: He gave long answers on foreign policy and told well-worn anecdotes. He used teleprompters for his opening remarks on NATO, which ran about eight minutes. Then the teleprompters lowered and he took a wide range of questions from 10 journalists about his mental acuity, foreign and domestic policy and -- mostly -- the future of his campaign.

“I believe I’m the best qualified to govern and I think I’m the best qualified to win," Biden said, adding that he will stay in the race until his staff says there's no way he can win.

“No one’s saying that,” he said. "No poll says that.”

Biden has explained away his June 27 debate performance as a bad night following a grueling month of international travel. Since then, he’s been out in public more, talking with voters and answering reporters’ questions. He even looks considerably less pale than he did two weeks ago.

“I’m determined on running but I think it’s important that I allay fears -- let them see me out there,” Biden said.

But his campaign on Thursday acknowledged he is behind, and a growing number of the president’s aides in the White House and the campaign privately harbor doubts that he can turn things around.

But they’re taking their cues from Biden, expressing that he is in 100 percent unless and until he isn’t, and there appears to be no organized internal effort to persuade the president to step aside. His allies were aware heading into the week that there would be more calls for him to step down, and they were prepared for it. But they felt like he met the moment Thursday, and demonstrated to lawmakers and the public he could do the job even though he's not known as a polished speaker.

The news conference extended into prime-time television coverage, and the major TV networks broke into programming for it, meaning millions of Americans were likely to have seen it.