Biden's horrific 'car crash' debate performance throws his entire presidency into doubt and sparks panicked calls from Democrats for him to step down - but president refuses to step aside as he visits a Waffle House

Joe Biden immediately faced calls to drop out of the presidential race following his debate with Donald Trump last night as the 81-year-old stopped off at a Waffle House after delivering a desperate performance in Atlanta. 

Several sources said his own party members are clamoring for their aged president to step down ahead of the election in November, with one anonymous Democrat telling NBC it was 'time to talk about an open convention and a new Democratic nominee'.

'Biden is about to face a crescendo of calls to step aside,' one Biden-backing strategist told The New York Times, while another Democrat put it even more flatly to the Washington Post.

'We're so f***ed,' they said. 'He has great material. He just cannot deliver a single line.' 

Evidently feeling peckish after having expended his limited mental energy on the stand, the president stopped off at the fast-food joint for a bite to eat with his wife Jill but was confronted by patrons over his sorry showing. 

'Some are concerned that you're not fit for the job... do you have any concerns about your performance?' one asked.

The President bit back: 'Well... it's hard to debate a liar,' claiming his Republican opponent trotted out a string of untruths and declaring that he believed he had performed 'well'. 

But he was powerless to distract from the reality of his performance.

The Democrat was combative and did not shy away from trading barbs with Trump, but as the debate went on it became painfully clear that he simply did not have the faculties to contend with his confident and smooth-talking Republican rival. 

Biden sounded tired and hoarse, frequently stumbled over his words and on one occasion completely lost his train of thought and trailed off into silence, prompting moderator Jake Tapper to dive in and rescue him. 

After spending much of her tenure defending him, even Vice President Kamala Harris was forced to admit Biden had 'a slow start' in an interview with pro-Democrat CNN's Anderson Cooper, who declared the president had 'disappointed' his supporters. 

Cooper noted that Biden's debate performance last night was visibly less convincing than when Harris herself debated him in the Democrat presidential primary back in 2020.

'He was a very different person on the stage four years ago when you debated him, that's certainly true is it not?' Cooper asked pointedly, noting it was 'scary' for Democrats who were watching to see their president melt on national television. 

But Harris sought to turn attention away from the debate and refused to be pulled into a conversation over the evident decline in Biden's mental capacity, ignoring repeated questions from Cooper that focused on the president's performance at the lectern. 

'Listen, people can debate on style points, but ultimately this election and who is the president of the United States has to be about substance,' Harris said.

'I got the point that you're making about a one and a half hour debate tonight. I'm talking about three and a half years of performance and work that has been historic,' she concluded.

'You can't honestly say... can you say that you are not concerned at all having watched the president's performance tonight?' Cooper asked. 

It was a slow start, that's obvious to everyone,' Harris repeated. 'I'm not going to debate that point. I'm talking about the choice in November.'

Harris also appeared on MSNBC to beat back the idea that Biden performed badly during the debate, and trotted out the same defence. 

'Well it was a slow start, there's no question about that, but I felt it was a strong finish,' she said during an interview with MSNBC's Rachel Maddow, before speaking with ABC.

Harris said she spent a lot of time with Joe Biden behind the scenes and insisted his supporters should judge him on the successes of his administration rather than his debating prowess.

'That's the Joe Biden I see every day. And I would urge folks to look at the record and look at the record of accomplishment,' she said. 

But Harris' seemingly impromptu media tour sparked speculation that the Biden campaign was deeply concerned about the fallout of the debate. 

'You don't send the Vice President of the United States out if you won the debate, typically,' former White House press secretary Jen Psaki said on MSNBC as the political panel laughed.  

Biden's supporters consistently express worry about the president's age and mental capacity and he did absolutely nothing to reassure them. 

One of the most shocking mishaps occurred just minutes into the debate when he lost his train of thought while making his case on tax rates and the number of billionaires in America.

The president embarked on a meandering ramble before trailing off and silently looking down at his lectern. After a pause of several seconds, he looked up and mumbled: 'We finally beat Medicare.'

At other times, Biden made some puzzling non sequiturs that seemed to undercut what the campaign has pushed as his strong points, including the economy and abortion rights. 

As Biden critiqued Trump's economic record, the president suddenly pivoted to Afghanistan and how Trump 'didn't do anything about that' - although the botched withdrawal of Afghanistan is widely considered one of the lowest points of Biden's presidency.

Later, as Biden singled out state restrictions on abortion, he confusingly pivoted to immigration and referred to a 'young woman who was just murdered' by an immigrant. It was unclear what point he was trying to make.

Trump has been reluctant to make light of Biden's age given that they were born only three years apart. 

He largely remained silent as Biden delivered his gaffes and allowed the Democrat to dig his own grave - but on a couple of occasions couldn't help but highlight his adversary's issues.

'I really don't know what he said at the end of that sentence,' he said at one point when Biden delivered a word salad about the border. 

'I don't think he knows what he said either.' 

Trump cruised through much of the debate, but stumbled at a few key points, including the question of how he would reassure voters that he would respect his oath of office after the January 6, 2021, attack on the U.S. Capitol.

Trump tried to avoid addressing the issue, defending the people who stormed the Capitol and blaming Biden for prosecuting them. 

'What they've done to some people who are so innocent, you ought to be ashamed of yourself,' Trump told Biden.

Trump warned that the members of the congressional committee that investigated Jan. 6 could face criminal charges, as could Biden himself.

Biden shot back: 'The only person on this stage who's a convicted felon is the man I'm looking at.'

Biden then brought Trump's recent criminal trial in New York over hush money payments made to porn star Stormy Daniels - charges on which he was convicted.

'I didn't have sex with a porn star,' Trump retorted flatly.

Biden also scored points off the Republican candidate when he attacked the former President for reportedly calling dead soldiers 'losers' and 'suckers' when he skipped a planned visit to a World War One cemetery in France. 

Referring to his late son Beau who was an army veteran, Biden declared: 'My son was not a loser, was not a sucker. You're the sucker. You're the loser.'