Biden defends mental health, vows to stay in race as House Democrats set weekend meeting

"I didn't listen to my instincts, in terms of preparing, and [had] a bad night," said Biden, who also referred to his performance as a "bad episode."

When Stephanopoulos noted that Biden had returned from an overseas foreign policy trip in Europe about 11 days before the debate and spent six days at Camp David beforehand, Biden replied, "I was sick, I was feeling terrible."

Asked if he watched the debate later, Biden briefly paused and then said, "I don't think I did, no." He said repeatedly that his performance was "nobody's fault [but] mine."

Biden also refused to entertain the idea of taking a cognitive or neurological test. "I get a full neurological test every day," Biden said, referring to the rigors of the presidency. When Stephanopoulos pressed him on why he hadn't taken had any cognitive assessments, the president replied, "No, no one said I had to."

The interview came on the same day that Biden defiantly rejected a growing chorus of Democrats, including top donors and allies, who are urging the 81-year-old incumbent to withdraw from the race.

Biden, under aggressive questioning from Stephanopoulos about whether he is capable of either beating Trump in November or serving another four years in the White House, maintained that he believes he is up to both tasks.

"I'm running again because I think I understand best what has to be done," Biden said in the 23-minute interview.

He appeared to foreclose any possibility of changing his mind, even in a scenario where party leaders and his close allies ask him to step aside.

"I mean, if the Lord Almighty came down and said, 'Joe, get out of the race,' I'd get out of the race," he said. "The Lord Almighty's not coming down."

Biden said he has spoken since the debate with Democratic leaders who did not tell him to withdraw.

But many Democratic lawmakers are still considering their next steps. House Minority Leader Hakeem Jeffries, D-N.Y., is holding a virtual meeting Sunday with the top Democrats on House committees, three sources told NBC News. The group is expected to focus on Biden, one of those sources told NBC.

Less than a half-dozen House Democrats so far have called on Biden to drop out of the race so far, but that number could grow over the weekend.

The president's remarks to Stephanopoulos echoed his earlier comments on the campaign trail that day.

"I am running and going to win again," Biden told a crowd of supporters during a speech in Madison, Wisconsin.

"They're trying to push me out of the race," Biden told the crowd. "Well let me say this as clearly as I can: I'm staying in the race."

Biden told reporters on an airport tarmac after the campaign event that he had spoken to "at least 20" members of Congress who are "telling me to stay in the race."

Biden's decision could set the campaign on a path of increasing tension with some of its top allies and donors who, spurred by concerns about Biden's health and abilities, have called for a new nominee to lead the Democratic Party into the November elections.

While Biden sounded consistently louder and clearer in Friday's remarks and interview than he did in last week's debate, he still occasionally slurred or fumbled over certain words and phrases.

On Capitol Hill, Democratic Sen. Mark Warner of Virginia, a longtime Biden ally, has launched a new effort to convene Democratic senators next week to discuss what Biden's path forward might be, NBC News reported.

Asked on the tarmac about Warner's effort, the president dismissed it. Warner, he said, "is the only one considering that. No one else has called me to do that."

On Thursday, Disney heiress and longtime Democratic donor Abigail Disney told CNBC that she will withhold donations until Biden withdraws.

On Wednesday, a group of business leaders corralled by the pro-Democracy Leadership Now Project urged Biden to step aside.

Editorial boards of multiple newspapers, including The New York Times, have issued the same call.

Questions are now swirling about how an alternative candidate, such as Vice President Kamala Harris, might take Biden's place as the new nominee.

The Trump campaign and Republican Party, in turn, have started ramping up attacks on Harris.

Harris told CBS News on Tuesday, "Joe Biden is our nominee. We beat Trump once, and we're going to beat him again. Period."

White House press secretary Karine Jean-Pierre held the line in a gaggle with reporters who peppered her with questions about Biden's capabilities during the flight to Madison.

"He said he had a bad debate," Jean-Pierre conceded. But "90 minutes should not overshadow his career, his three-and-a-half [year] tenure as president."

Biden, she added, "is resolute, strong [and] thinking as clearly as he used to."

But that solid front — buttressed by subsequent statements of support from Democratic governors and other allies — has done little to tamp down the anxieties of Trump's opponents.

Biden, the oldest president ever to serve and would be 86 at the end of a second term, was already struggling before the debate to boost his limp approval ratings.

National polls have consistently showed a neck-and-neck race, but some surveys gave Trump an edge in the key swing states that carried Biden to victory in 2020. Meanwhile, wide swaths of voters have repeatedly expressed concerns about Biden's age and fitness for office.

After the debate, polls from major media outlets, including The New York Times and The Wall Street Journal, all showed Trump gaining on Biden.