Joe Biden 'in this race to win,' campaign says as reports he may step down intensify

US 'does not really have a precedent like this', expert says of growing presidential election dispute

US President Joe Biden is under pressure from some Democrats to withdraw from the presidential election and let his party nominate a different candidate. AP

US President Joe Biden's campaign is entering the weekend on the defence against a growing chorus from fellow Democrats for him to abandon his re-election campaign.

Mr Biden's campaign chairwoman Jen O’Malley Dillon on Friday insisted that he is “in this race to win”.

“Absolutely, the President’s in this race,” she told MSNBC, adding that Mr Biden “is more committed than ever to beat Donald Trump”.

Democratic Senator Chris Coons told the Aspen Security Forum Colorado that he disagrees with people who believe Mr Biden is not “strong enough” to be president.

Mr Coons also added that he believes Mr Biden “is weighing what he should weigh, which is who is the best candidate to win in November and to carry forward the Democratic Party's values and priorities in this campaign”.

“I am confident he is hearing what he needs to hear from colleagues, from the public, from folks,” Mr Coons said.

The comments came after The Washington Post reported on Thursday that former president Barack Obama and former speaker of the House of Representatives Nancy Pelosi, both influential Democrats, had expressed doubts over Mr Biden's future as a candidate.

Congressman Morgan McGarvey of Kentucky became the latest party member to call on Mr Biden to leave the race, saying the President is "an empathetic and effective leader", and there is "no joy" in saying he is not the best candidate to run against Mr Trump.

If Mr Biden were to step aside ahead of the Democratic convention in August, the US does not “really have a precedent like this”, said Patricia Crouse, a practitioner in residence in public administration and political science at the University of New Haven.

“This is very different, because we're in the middle of the campaign,” she told The National.

The Biden-Harris ticket is not official until after they are certified as the nominees at the convention, and the Democratic National Committee has specific rules about how a presumptive nominee can be replaced in the event of a vacancy before or during the convention.

But Ms Crouse expects that, if Mr Biden were to step aside, it would happen before the convention and Democrats would move to put Vice President Kamala Harris at the top of the ticket.

“By doing so, she has full access to all of Biden's campaign funds. If you go to the convention and you nominate someone new at the convention, that person can't just access Biden's money. They'd be starting campaign from scratch in July or August,” she said.

Despite growing calls from corners of the Democratic Party for Mr Biden to stand down, he still has fierce support from many.

CBS News correspondent Bob Costa on Thursday reported, citing unnamed sources, that Mr Biden's inner circle was “furious” at the mounting criticism over the course of the last week.

Progressive Congresswoman Alexandria Ocasio-Cortez, who quickly endorsed the President after his debate performance, meanwhile dedicated an hour-long Instagram live to defend his candidacy on Thursday evening, conceding that she does not “know what's going to happen”.

According to a poll this week from the AP/Norc Centre for Public Affairs, nearly two thirds of Democrats say they think Mr Biden should withdraw from the presidential race and let his party nominate a different candidate.

Other polls show that Donald Trump's lead over Mr Biden is growing, at 52-47, compared to 50-48 earlier this month.

“I've heard people say that the Democrats might as well quit now, that's crap. Elections can change overnight,” Ms Crouse said.

“I'm not writing off anybody now, and I don't think anybody should be taking a victory lap.”

But there are some key lessons she said the Democrats should learn from this chaotic moment, including abandoning the notion that “candidates are somehow owed the presidency because they were vice president, or they're owed the presidency because they served in somebody's administration”.

“The problem is we've moved to these candidate-centred elections, and the parties have very little to say now really about choosing candidates,” Ms Crouse added.

“I think the parties probably need to take back some of that power.”