US election 2024: will Joe Biden step aside and who could replace him as Democratic nominee?

Joe Biden’s fitness for office is under intense scrutiny after a debate (on June 27) with Donald Trump saw him give shaky answers and lose his train of thought. 

The US president will celebrate his 82nd birthday not long after November’s election — and so-called senior moments have led to his detractors calling for him to stand aside.

Mr Biden’s team has put the interview down to the president having a cold. Democrats will be quick to point out that his election rival Mr Trump is no spring chicken at 78.

“I didn’t have my best night, but the fact is that you know, I wasn’t very smart,” Mr Biden said.

He added that he had debated following several flights through various time zones, causing jet lag.

But his comments are unlikely to dampen fevered speculation about his future.

So what are people saying about this and who could replace him if he does leave the US presidential race?

Here’s everything you need to know.

Why do some people say Joe Biden should step down?

Mr Biden “had only one job” in the debate, the Standard’s Jack Kessler wrote.

“[This was] to demonstrate to the American people, particularly those living in Pennsylvania, Wisconsin, Georgia and Arizona, that he is not too old to be president.

“He couldn’t do it,” he said.

After his head-to-head with Mr Trump, CNN asked viewers who had won — and 67 per cent said it was the Republican nominee, while 33 per cent backed the incumbent Democrat.

At one point, Mr Biden’s voice trailed when speaking about Trump’s economic record. He finished his remarks by making the seemingly irrelevant comment: “We finally beat Medicare.”

The performance was so alarming that US polls are now in favour of Mr Trump despite the former president’s criminal conviction. 

Latest polling suggests that voters feel Mr Biden is too old and should not run. Even 51 per cent of Democrat voters said a new candidate should be found.

Mr Biden is already the oldest ever president, having taken the record from Ronald Reagan — who lasted until age 77. Mr Trump is already third on the list and, would claim the unwanted title if he becomes president again.

As AP reported of Mr Biden: “He is often sharp and focused. But he also has moments, particularly later in the evening, when his thoughts seem jumbled and he trails off mid-sentence or seems confused. Sometimes he doesn’t grasp the finer points of policy details. He occasionally forgets people’s names, stares blankly and moves slowly around the room.”

While such moments are common for someone his age, it is not a good look for a man attempting to become the most powerful in the world.

Will Joe Biden step down?

Mr Biden has insisted he will not step down.

“We understand the concerns. We get it,” White House press secretary Karine Jean-Pierre said this week. But she emphasised Mr Biden has no intention of stepping away from the campaign. “The president is clear-eyed and he is staying in the race.”

Mr Biden’s doctor Dr Kevin O’Connor said in February that the president was “fit for duty”.

Dr O'Connor said Mr Biden was adjusting well to a new device that helps control his sleep apnoea. He said he had experienced some hip discomfort but also works out five times per week.

However, Mr Trump is confident he has the upper hand on his embattled rival.

“I kicked that old broken-down piece of crap,” the former president boasted on July 3.

He then made an unsubstantiated claim, while out on a golf course, that Mr Biden had “quit the race” and that the Democrats would instead put forward Vice President Kamala Harris.

“I think she’s gonna be better,” he said. “She’s so bad. She’s pathetic. She’s so fxxxxxx bad.”

Who could replace Joe Biden?

For clarification, any names are purely speculative given Mr Biden’s apparent desire to stay in the job.

The Democratic Party will officially choose him as its presidential candidate at its convention on August 19, all being well.

If Mr Biden stands down voluntarily before then, it would spark a snap party contest to replace him.

It would be unprecedented for the Democrats to force someone out. There are limited powers to do this now that he has won the backing in a party vote.

However, here are some of the frontrunners in a hypothetical leadership contest:

Kamala Harris

Ms Harris would take over as president should her boss quit — but that would not mean she would be automatically in the frame to fight for the election.

Her experience might make her an obvious candidate but her poll ratings count against her.

Gavin Newsom

The governor of California is coming to the end of his second, and final, term in office and is said to be eyeing up the top job.

However, the 57-year-old has also performed poorly in polls and projections say he would lose a run-off against Mr Trump.

Michelle Obama

The former first lady has a large personal brand and big-name recognition but has limited political experience.

She has steered clear of backing Mr Biden in the election run-up over an alleged feud about how the president’s family handled Hunter Biden’s split with her friend Kathleen Buhle.

Other potentials

Gretchen Whitmer is a rising star in the party and governor of Michigan while Josh Shapiro, the Pennsylvania governor, is also reportedly in the frame.

Beto O'Rourke, the former Texas congressman, was once touted as a future president but has lost his last three election votes.

Long shots include Robert Kennedy Jr, Hillary Clinton, and Dwayne Johnson.