US President Joe Biden is poised to make a “major announcement” about his future, according to claims from senior Democrats.

It came amid reports the President was increasingly isolated with many senior-ranking White House and campaign officials privately believing that he must abandon his race for a second term – and soon.

“The next 72 hours are big,” one Democratic governor told aides, and was reported by CNN as saying on Thursday (US time).

“This can’t go on much longer.”

Reports suggest that Biden, who has been under increasing pressure to quit the presidential race, will make his announcement after the Republican National Convention concludes in Milwaukee.

He is reportedly relying on just a handful of his closest aides as he mulls his decision.

“Everyone is saying it privately,” one senior Democrat told CNN. “People see and feel the walls closing in.”

If Biden quits, Vice-President Kamala Harris is the frontrunner to become the Democratic nominee for November’s race to the White House against Donald Trump.

Other possible contenders include Arizona senator Mark Kelly, Kentucky Governor Andy Beshear and North Carolina Govenor Roy Cooper.

The latest update came as Biden, who is isolating at home in Delaware with Covid, was said to be taking taking calls to step aside seriously. Multiple sources said his exit could come within days.

“His soul searching is actually happening, I know that for a fact,” one said.

“He’s thinking about this very seriously.”

President Biden continues to conduct the business of the American people. An update from Dr. Kevin O’Connor, Physician to the President: pic.twitter.com/zrAvbVgzxP

— The White House (@WhiteHouse) July 18, 2024

Biden, 81, has faced increasing pressure from heavyweights in his party to cede his position at the top of the ticket after his shoddy debate performance against Trump renewed fears about his age and ability to win in November.

Publicly, Biden has pushed back defiantly, arguing that he has won millions of votes in primary races in recent months and is Democratic voters’ choice. As recently as Wednesday, he vowed “I am all in” the 2024 race.

But one Democratic congressional aide said the writing appeared to be on the wall after senior figures – including Senate Majority Leader Chuck Schumer, former House speaker Nancy Pelosi, and former president Barack Obama – reportedly urged him to drop out.

“It feels like it’s a matter of … when, not if,” the aide said.

Democratic Senator Chris Coons of Delaware, a close Biden ally, told CNN on Thursday (US time) that Biden would be “resting and reflecting” this weekend as he recovered from Covid.

“President Biden deserves the respect to have important family conversations with members of the caucus and colleagues in the House and Senate and Democratic leadership and not be battling leaks and press statements,” he said.

Biden had asked for information on polling data and was weighing the input of those he trusted and admired, Coons said, adding he thought the President remained the best candidate for 2024.

Biden’s campaign is focusing on three out of seven battleground states after the debate, a narrow path to victory. But it continues to publicly reject suggestions that he is ready to step aside.

“He is not wavering on anything. The President has made his decision,” deputy campaign manager Quentin Fulks said in Milwaukee.

“Joe Biden has said he is running for president of the United States. Our campaign is moving forward.”

However, another source, a Biden campaign official, said the opposite. “Yes, it’s over. Just a matter of time.”

Democratic Senator John Hickenlooper of Colorado said he believed Biden was working toward a decision on whether to stay in the presidential race.

“Joe Biden has always put the country first. He’s done what’s best for America … I think he’ll keep doing so,” Hickenlooper told Reuters on Wednesday, adding there were indications it would be best for the US if he stepped aside.

-with AAP