President Joe Biden’s family has reportedly discussed a possible exit plan as he faces continued pressure from fellow Democrats and big money donors to end his floundering re-election campaign.

NBC reports that members of the Biden clan discussed what an exit plan might look like and how he would want to end his campaign on his own timing.

The plan would be carefully calculated and should put the party in the best position to beat Donald Trump, NBC quoted two sources familiar with the discussions.

It would have to consider the impact of the campaign on Biden’s health, his family and the stability of the country.

The notion of Biden considering stepping aside is a significant development given the president has steadfastly opposed calls from within the party to “pass the torch” to a new Democrat nominee.

Biden and top aides on Friday again vowed to continue with the campaign, even as major donors signalled they were unwilling to open their chequebooks.

Biden’s campaign hoped to raise some $US50 million ($75 million) in big-dollar donations in July for the Biden Victory Fund but was on track for less than half that figure as of Friday, according to two sources familiar with the fundraising efforts.

The campaign called reports of a July fundraising slump overstated, noting that it anticipated a drop-off in large donations due to vacations. It said the campaign still has 10 fundraisers on the schedule this month.

The crisis of confidence in Biden’s ability to win has placed a huge spotlight on Vice President Kamala Harris, widely believed to be the most likely replacement if he steps down.

CNN reports that consensus is solidifying around Harris within the Democrats.

Her fundraising events, including one on Saturday in Provincetown, Massachusetts, are getting added interest from donors who want to signal they are willing to coalesce around her potential bid for the White House, according to three Democratic fundraisers.

The fundraiser is being hosted by celebrity wedding planner Bryan Rafanelli, with Transportation Secretary Pete Buttigieg expected to speak, according to a person familiar with the event.

Thirty-five congressional Democrats, representing more than 10 per cent of the party’s members in Congress, have now publicly called on Biden, who is isolating at his Delaware home with a case of COVID-19, to drop out.

Democratic former President Bill Clinton and former US Secretary of State Hillary Clinton have privately been supportive of Biden’s decision to stay in the race and have been actively encouraging donors to stay with him, NBC News reported on Saturday, citing two sources familiar with the matter.

Separately, US Representative Mark Takano of California on Saturday became the latest Democratic congressman to call on Biden to step aside as a presidential candidate.

Harris assured major Democratic donors on Friday that the party would prevail in the presidential election as more lawmakers called for her running mate, Biden, to stand down.

“We are going to win this election,” she said on a call arranged on short notice to calm donors, according to a person on the call.

“We know which candidate in this election puts the American people first: Our president, Joe Biden.”

Harris attended the call “at the direct request of senior advisers to the president,” one of the people said, an account confirmed by another person familiar with the matter.

Trump’s first post-shooting rally

Meanwhile, Donald Trump will hold his first campaign rally since he narrowly escaped an assassination attempt and fresh from his nominating convention where his takeover of the Republican Party was cemented.

Trump will appear in Grand Rapids, in the battleground state of Michigan, along with his new vice-presidential pick, Ohio US senator JD Vance.

It will be their first campaign event together as the official Republican presidential ticket.

Republican Party officials said during Trump’s nominating convention in Milwaukee this week that his brush with death last Saturday had changed him, and when he made his acceptance speech on Thursday night he would call for national unity.

While Trump began the address with a call for unity and national healing, much of his speech was his well-known list of grievances and attacks on opponents.

It is unclear what type of a speech Trump will deliver on Saturday (US time) but his diehard supporters typically flock to such events to hear Trump’s more traditional inflammatory rhetoric.

Trump and Vance will take the stage in Grand Rapids with the Republican Party unified behind them after this week’s nominating convention.

The rally in Grand Rapids will be in an indoor arena, unlike the event in Butler, Pennsylvania last weekend, which was outdoors.

At that event, the gunman was able to scale the roof of a building outside the Secret Service perimeter before opening fire on Trump, clipping his ear, killing a rally-goer and wounding several others.

The US Secret Service, which is responsible for protecting Trump, declined to comment on security for the Grand Rapids event. An investigation is under way into the security failures at the Butler rally.

“The Secret Service does not discuss the means and methods used for our protective operations,” the agency said in a statement.

Trump gave a detailed account of his narrow brush with death in his convention speech on Thursday, telling the audience that he was only talking to them “by the grace of almighty God”.

-with AAP