US President Joe Biden was facing fresh doubts from Democratic Party leaders over the viability of his candidacy. 

Former President Barack Obama has privately expressed concerns that Biden's path to victory has greatly diminished, several people familiar with the private conversations told the Associated Press in a report published on Thursday.

The Washington Post reported that Obama thinks Biden should "seriously consider the viability of his candidacy."

Former House Speaker Nancy Pelosi is reportedly among those who have privately told Biden he cannot win and that he is putting Democrats' chances at winning control of the House of Representatives at risk. 

Citing several sources close to the president, The New York Times on Thursday reported that Biden is beginning to accept the idea that he may have to drop out of his reelection campaign.

However, Biden's campaign co-chair Cedric Richmond dismissed the report in an interview to MSNBC and said, "The New York Times reporting is absolutely wrong. 

"The president has said that he is running and it's the end of story," he added.

Biden and Vice President Kamala Harris were set to face the Republican ticket of former President Donald Trump and Senator JD Vance in the November 5 election.

Biden reportedly 'soul searching'

After the reports, the Biden campaign remained defiant, insisting that the president "is not wavering on anything."

"Our campaign is not working through any scenarios where President Biden is not the top of the ticket," Biden's deputy campaign manager Quentin Fulks said.

But privately, Biden is reportedly considering his colleagues' advice.

"His soul searching is actually happening, I know that for a fact," a source who requested anonymity told the Reuters news agency. 

"He's thinking about this very seriously." 

Pelosi reportedly concerned

Multiple news reports say former Speaker Nancy Pelosi spoke with Biden about a week ago, telling the president that she and other members of the Democratic Party were concerned about him staying in the race.

CNN and The New York Times reported that Pelosi privately told Biden that he cannot win and could harm Democrats' chances of regaining a majority in the House.

The Washington Post said that compared to Obama, "Pelosi has taken an even more active role behind the scenes."

Late Thursday, Montana Senator Jon Tester became the second Democrat in the chamber to support the ideo of Biden dropping out of the election race.

"I believe President Biden should not seek reelection to another term," he said in a statement.

Biden's campaign has been hampered by speculation about his age, his physical health and his cognitive ability in recent weeks. His personal doctor, Kevin O'Connor, said on Thursday that he was still experiencing mild COVID-19 symptoms.

Political website Axios reported that Biden could drop out as soon as the weekend. NBC also quoted a person close to Biden as saying: "We're close to the end."

zc/lo (AP, AFP, Reuters)