How Democrats would replace Biden as their candidate if Joe steps aside after debate disaster - and how the Obamas will play a key role in the decision

Joe Biden could be replaced as the Democrats' presidential candidate within weeks - with the Obamas and Clintons waiting in the wings to force him out if he refuses to step aside before the party convention in August, MailOnline can reveal.

Biden, 81, fumbled and stumbled in the first presidential debate, losing his thread, sounding hoarse and searching for words as Trump swatted at his arguments. 

Many Democrats will now ramp up calls for Biden to step aside in favour of another candidate ahead of the party's national convention in August. Biden would then not fight Trump in November but would remain President until January, when the election winner would take over.

Senior party leaders are privately pushing for California Governor Gavin Newsom or Michelle Obama to step in. The Constitution prevents a prior 2-term President from running again, so Barack Obama must watch from the sidelines. Other favourites with the bookmakers are Biden's deputy Kamala Harris, Governor of Michigan Gretchen Whitmer and Wes Moore, Governor of Maryland.

But there are real fears that Biden will refuse to stand aside - and it could take an intervention from top Democrats such as Bill and Hillary Clinton, Barack Obama, Nancy Pelosi and Chuch Schumer to get Biden to consider stepping aside in the coming days. Hillary, who beat Biden to the Democrat nomination in 2016, has already said his age is a ‘legitimate issue’. 

Jill Biden is also being viewed as a roadblock because she is also said to be determined for her husband to fight the election in November -  even with the question marks over his health.

Mr Biden dismissed calls to leave the race last night - insisting the debate with Trump 'went well' - but behind the scenes the Democrats are in chaos with many pushing the panic button. 

It possible to replace Biden as the Democratic presidential nominee - but it is complicated due to a lack of time and the danger of civil war in the party.

The Democratic National Convention will be held in Chicago from August 19 to 22. Each state sends a certain number of delegates to the national convention.

If Biden stepped down, the party would have to hold a series of votes among the delegates until one person got the 1,976 to be the nominee.

This would likely result in a massive floor fight for votes that would take place over multiple days and dominate news coverage. 

Biden has 3,894 pledged delegates and it only takes 1,976 to be the nominee.  

Under party rules, delegates allocated to a candidate based on their primary wins are bound to their candidate on the first ballot at the convention. And that first ballot usually ends up in a nominee.

So legally Biden's delegates have to vote for him. 

However, if Biden were to drop out that would mean the nomination would be decided on the floor of the Democratic National Convention in August. 

His delegates would become  'uncommitted' and able to vote for any candidate they liked.

Vice President Kamala Harris would not automatically be the nominee nor would she have ownership of Biden's delegates because she was not on any primary ballots. Biden was.

But she would be the likely favourite given her status as his running mate.

Democrats, however, could choose any contender including any governor such as Gavin Newsom of California, Gretchen Whitmer of Michigan, J.B. Pritzker of Illinois, Josh Shapiro of Pennsylvania and Wes Moore of Maryland.

Or one of the people that ran in 2020: Transportation Secretary Pete Buttigieg, Senator Amy Klobuchar of Minnesota and Senator Cory Booker of New Jersey. 

Things would be easier if Biden were to drop out of the race after the convention.

If that happened, the party's main committee would pick the nominee, avoiding a convention floor fight. 

Under party rules, the Democratic National Committee has the authority to choose a new candidate if either member of the ticket — the presidential or vice-presidential nominee — withdraws or dies.

Party Chairman Jaime Harrison would consult with Democratic leaders in Congress and in the Democratic Governors Association and report his findings to the committee, which would have the final say. 

Kamala Harris would not automatically be elevated to the top of the ticket. 

The last floor flight at a Democratic Convention was in 1968 and was such a disaster many new rules were added to the party's platform to keep such chaos from happening again.

That year, Democrats were worried their very unpopular president - Lyndon B. Johnson - could not win another term.

Johnson, under party pressure, chose not to run. But the frontrunner for the nomination - Bobby Kennedy - was killed by an assassin in June of that year.

Johnson's vice president Hubert Humphrey and Eugene McCarthy had also been running. Neither had enough delegates to win the nomination on the first ballot at the convention, which was in Chicago (the same as this year's Democratic convention). 

The floor fight began with Humphrey ultimately winning the nomination. It was a huge controversy with riots breaking out all over the city. Humphrey ultimately lost the general election to Richard Nixon.

Republicans have been issuing warnings about the increasingly doddery Biden for years. Donald Trump was insisting before the 2020 election that his gaffe-prone political rival had slipped into senility.

Back then, such jibes were dismissed by Democrats as tasteless scaremongering. But now the Left, too, are expressing their fears.

That concern has sky-rocketed following a string of absent-minded ‘senior moments’ from the 81-year-old president in the past few days, revealing a seemingly endless capacity for confusing the names of world leaders, even ones separated by decades.

And the TV debate with Trump last night has sparked total chaos. 

James Carville, a veteran Democrat strategist who masterminded Bill Clinton’s successful 1992 campaign, said witheringly that Biden passing on a Super Bowl Sunday interview this year was a sign his staff had little confidence in him.

The evidence has been accumulating. Biden mixed up Francois Mitterrand, a French President who died in 1996 with Emmanuel Macron.

Investigators who quizzed Biden said that his memory ‘appeared to have significant limitations’ and he ‘did not remember, even within several years. when his son Beau died’. 

Biden could also not remember when he was Vice President or the details of a debate about sending extra troops to Afghanistan, they said.

Repeated polls have shown that both Republicans and Democrats have deep misgivings about Biden’s age and his ability to serve a second term. Sleepy Joe - as he was dubbed by Trump - is already easily the oldest person to become president in US history. If he reclaims the White House, he would be 82 at the start of his second term in January 2025. (If Trump wins, he would be 78.)

A recent poll showed a staggering 71 percent of swing-state voters - the people who will very likely decide the outcome of November’s presidential election - agreed that Biden ‘is too old to be an effective president’. Another new poll found 76 per cent of all voters have concerns about the President having the physical and mental strength for a second term.

Biden’s long-established reputation for embarrassing gaffes and mis-statements - in 2018 even he described himself as a ‘gaffe machine’ - has in one sense benefited him up until now, allowing his team to explain away mistakes as his Uncle Joe folksy, goofy charm.

But the dramatically increased frequency of his verbal stumbles is causing alarm. And it has been accompanied by evidence of physical frailty, too. Since 2021 he has reportedly tripped eight times while navigating the steps of Air Force One, the presidential jet, including three times on a single flight to Atlanta.

In 2022 he fell off a bicycle after getting caught up in his pedals; in 2023 he stumbled descending a small set of steps at the G7 summit in Hiroshima, Japan; later that year he tripped over a sand bag and fell on stage at an Air Force academy graduation ceremony. And when the stairs to Air Force One were shortened last year so that he entered the plane at a lower level, Biden tripped on them, too.

The two brain aneurysms Biden suffered in 1988 were fully treated and he showed no signs of mental trouble as a result, according to a surgeon who operated on him.

In an annual physical last year, a White House doctor Kevin O’Connor attributed his stiff gait to ‘significant spinal arthritis, mild post-fracture foot arthritis and a mild sensory peripheral neuropathy of the feet’. However, the doctor refused to comment on his mental acuity.

One of Biden’s most frequent mistakes has been to refer to Vice President Kamala Harris as ‘President’. And that, say some Washington insiders, may be a Freudian slip.

They believe that the main reason that Biden is intent on running again is because he knows that if he steps down and is succeeded by Harris - widely regarded as useless and even more unpopular than him - the Democrats have an even worse chance of beating Trump.

There is a way out, however: he could hang on, win the party nomination and then, at the Democratic National Convention in August, announce he’s withdrawing and not endorse a replacement. The convention, made up of party bigwigs rather than the idealistic rank-and-file who decide the primaries, can then choose someone who has the best chance of winning over crucial swing voters and vanquishing The Donald.

That would mean Harris would likely be swept aside by stronger contenders such as California governor Gavin Newsom or Michigan governor Gretchen Whitmer (although both may be a little too woke for independent voters). Some haven’t given up hope that Michelle Obama may overcome her oft-expressed reservations and run.

All of this, however, remains wishful thinking for now. And, given that it would be very difficult to force Biden out, it depends on him playing ball. Which brings us back to square one - because privately he’s understood to believe that he’s the only Democrat who can beat Trump.