US President Joe Biden’s family used a gathering at Camp David to urge him to stay in the race and keep fighting, despite his dreadful debate performance, and some members criticised how his staff prepared him for it, according to people familiar with the discussions.

Mr Biden spent Sunday sequestered with first lady Jill Biden, his children and his grandchildren.

It was a previously scheduled trip to the presidential retreat in Maryland for a photo shoot with Annie Leibovitz for the forthcoming Democratic National Convention.

But the gathering was also an exercise in trying to figure out how to quell Democratic anxiety that has exploded after Thursday’s performance.

While his family was aware of how poorly he performed against Donald Trump, they also continue to think he is the best person to beat the Republican presumptive nominee.

They also believe he is capable of doing the job of president for another four years, according to people who were not authorised to speak publicly about internal discussions.

Among the most vocal: Jill Biden and son Hunter, whom the president has long gone to for counsel and advice.

Both believe the president should not bow out when he is down, and believe that he can come back from what they see as one subpar performance.

The family questioned how he was prepared for the debate by staff and wondered if they could have done something better, the people said.

Mr Biden’s campaign has spent the days since the debate, in which he appeared raspy, trailed off, and at times gave convoluted answers, working to keep donors on board as Democrats increasingly questioned whether he should stay in the race.

At this point in the delegate process, Mr Biden would probably have to decide to drop out for there to be a new nominee. And the people he listens to most in the world, his wife and son, are telling him to stay in.

Even before the debate, the age of the 81-year-old Democratic president had been a liability with voters, and the prime-time faceoff appeared to reinforce the public’s deep-seated concerns before perhaps the largest audience he will have in the four months until election day.

CNN said more than 51 million people watched the debate.

While the president was huddled with his family, prominent Democrats rallied to deliver a public show of support for his campaign on Sunday.

“I do not believe that Joe Biden has a problem leading for the next four years,” said one close ally, Democratic representative James Clyburn of South Carolina said. “Joe Biden should continue to run on his record.”

But concern simmered among some Democrats that Mr Biden’s campaign and the Democratic National Committee were not taking seriously enough the impact of the debate.

Former Iowa senator Tom Harkin, who worked for more than two decades with Mr Biden in the Senate, called the debate “a disaster from which Biden cannot recover”.