US President Joe Biden says he is ready to return to the campaign trail next week, but he faces a growing chorus of Democrats calling for him to step aside.

Mr Biden has been resting at his beach home in Delaware since contracting Covid, and the White House said on Saturday his symptoms “continue to improve steadily”.

But his time away from the spotlight has done nothing to diminish the focus on him, with Democrats churning over whether he should stay in the race for the White House after his dismal debate performance raised open questions about the 81-year-old’s ability to mount a convincing campaign to defeat Donald Trump.

Nearly three dozen Democrats in Congress have now said it is time for Mr Biden to leave the race.

There is also party turmoil over whether his Vice-President Kamala Harris is next in line for the job or if a “mini-primary” should be quickly launched to choose a new nominee before the Democrat convention in August.

Kamala Harris, centre, surrounded by children and supporters
US vice-president Kamala Harris has led the Democrats’ campaign this week in Joe Biden’s absence (Erin Schaff/The New York Times/AP)

Ms Harris hit the campaign fundraising circuit on Saturday in Provincetown, Massachusetts, and picked up a nod from the state’s prominent Democratic senator Elizabeth Warren. She said before the visit that if Mr Biden was to step aside, his vice-president is “ready to step up”.

At the event, which organisers said raised two million US dollars (£1.5 million) and was attended by 1,000 guests, Ms Harris did not mention the calls for Mr Biden to leave the race or for her to replace him, instead repeating one of her regular campaign lines: “We’re going to win this election.”

To a cheering crowd, she added: “Do we believe in freedom? Do we believe in equality? Do we believe in the promise of America? Then are we ready to fight for it? When we fight, we win.”

Later as she boarded her plane to leave, Ms Harris flashed a thumbs-up after reporters asked how Mr Biden is doing as he recovers from Covid-19.

Installing Ms Harris at the top of the ticket, which would be a history-making moment for the party elevating the first woman, black person and person of South Asian descent as its presidential nominee, is not at all certain.

Head and shoulders of Nancy Pelosi speaking at a lectern
Nancy Pelosi is a key voice within the Democrats (Karl B DeBlaker/AP)

Officials from the highest ranks, including Speaker Emerita Nancy Pelosi, prefer an open process, some believing it would strengthen any Democratic nominee to confront Republican Mr Trump.

Speaking herself to a room full of North Carolina Democrats on Saturday, Ms Pelosi did little to quell speculation on Mr Biden’s path forward.

An event billed as the annual “Unity Dinner” came during a time of significant national discord within the Democrats.

Ms Pelosi gave a speech largely absent of mentions of Mr Biden’s presidential bid.

She spent most of her address recounting battles over budget and policy in the US House, highlighting the importance of funding public education and reiterating the dangers of the Republican agenda.

When she did mention Mr Biden, it was mostly to tout his administration’s policies.

At the end of her speech, Ms Pelosi shifted to discussing the party’s plans in the coming months and chose to focus on Democratic mobilisation efforts rather than who to mobilise behind.

“Are you ready for a Democratic president?” Ms Pelosi said amid cheers. “I thought so.”

House Speaker Mike Johnson predicted that Republicans would challenge whether Democrats can legally replace Mr Biden as the nominee if he steps down.

“I think they have got legal hurdles in some of these states, and it’ll be litigated, I would expect, on the ground there and they will have to sort through that. They have got a real problem,” Mr Johnson said on CNN’s State Of The Union.

On Sunday, Senator Joe Manchin of West Virginia – who became an independent in May after years as a Democrat – urged Mr Biden to drop his re-election bid and focus instead on the remaining months of his presidency.

He told CNN: “I came to the decision with a heavy heart that I think it’s time to pass the torch to a new generation.”

The Biden campaign is touting a joint letter by state Democratic Party chairs from seven swing states that urges Democrats to unite around Mr Biden.

“We understand the anxiety. But the best antidote to political anxiety is taking action. You can’t wring your hands when you’re rolling up your sleeves,” said the party chairs from Wisconsin, Michigan, Pennsylvania, North Carolina, Georgia, Arizona and Nevada.