Pressure is building on Joe Biden to end his re-election campaign after former president Barack Obama told allies his path to victory had greatly diminished.
Mr Obama has “concerns” about his ability to remain as the Democratic nominee, two people familiar with his thinking told NBC News, Sky’s US partner.
He sees Mr Biden’s route to victory in November “getting harder”, said one of the sources.
Meanwhile, Mr Biden has reportedly said he would consider dropping out of the 2024 race if he was diagnosed with a “medical condition” by a doctor.
In a pre-recorded interview with BET News, he said he would re-evaluate his campaign “if I had some medical condition that emerged”.
“If doctors came to me and said, you got this problem and that problem,” he added.
He also acknowledged he had run for the presidency as a “transitional candidate” and had expected to “pass it on to somebody else”.
But he said he had not expected how divided the US would become, adding: “There’s more to do and I’m reluctant to walk away from that.”
A source close to President Biden told NBC News the leader was responding to the building pressure, saying: “Can we all just remember for a minute that these same people who are trying to push Joe Biden out are the same people who literally gave us all Donald Trump?
“In 2015, Obama, Pelosi, Schumer pushed Biden aside in favour of Hillary; they were wrong then and they are wrong now.”
They suggested the US leader was “more in touch with actual Americans than Obama-Pelosi-Schumer”.
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Top Democrats call for Biden to drop campaign
Several top Democrat leaders have reportedly privately pushed him to drop his campaign.
US Senate majority leader Chuck Schumer, House minority leader Hakeem Jeffries and former House speaker Nancy Pelosi have told Mr Biden they are concerned he will not only lose the White House but also cost the party any chance of winning back the House of Representatives in the 5 November election, several reports said.
So far 20 out of 264 Democrats in Congress have called on the 81-year-old president to drop out following his dire performance during a debate against Donald Trump, 78, last month.
Mr Biden has insisted he will not back down, arguing he beat Mr Trump before and he will do so again.
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Biden heard sounding unwell during interview
Asked about reports Mr Biden might be coming around to the idea of leaving the race, his deputy campaign manager Quentin Fulks told the Associated Press news agency: “He is not wavering on anything.”
It comes after Mr Biden tested positive for COVID-19 during a campaign visit in Nevada, forcing him to return to his home in Delaware to work in isolation.