Hillary Clinton upbraided President Joe Biden for making a 'terrible mistake' in running for reelection in 2024, a move that ultimately greased President Donald Trump's return to the White House. 

Clinton sat down with The New Yorker's David Remnick Monday night at 92NY for a taping of The New Yorker Radio Hour. 

The Democrats' 2016 nominee, former Secretary of State, US Senator and First Lady explained to Remnick how she thought the last presidential election should have played out. 

'He made a terrible mistake for himself, his legacy and for the country,' Clinton said of Biden. 'He had said that he would not run again. And counterfactual narratives are always a bit tricky.'

When running for President in 2020, the then-77-year-old described himself as a 'bridge' candidate - which many Americans interpreted as a soft commitment to only serving one term. 

With Trump announcing he would again seek the White House in November 2022 - the earliest campaign announcement in history - Biden decided to seek reelection, officially announcing his 2024 bid in April 2023. 

'But I believe if he had kept to that plan and said, in, say, the late summer of '23, that he wasn't going to run, that he was going to pass, you know, the torch to the next generation, we would have had a real contest,' Clinton continued. 

'And very sadly, I believe whoever emerged from that contest, whether it was the Vice President or a governor or a senator or anybody else, would have beaten Donald Trump,' she added. 

Only self-help guru Marianne Williamson and Representative Dean Phillips decided to challenge Biden in the 2024 Democratic primaries. 

With no real opposition, Biden was set to become the Democratic nominee until his disastrous late June debate performance against Trump prompted members of his party to start calling on him to drop out.

He stayed in the race until late July, and then hastily bowed out and endorsed Vice President Kamala Harris. 

Harris had just 107 days to mount a campaign against Trump. 

She ultimately lost every swing state to the Republican.

'So I think it was a terrible miscalculation on the part of President Biden,' Clinton said.

'But once he didn't move, and did not, you know, admit that he had said he was going to step aside and then decided not to, and held on for as long as he did, we were in a terrible dilemma,' the 2016 Democratic nominee said. 

In her new book, View from the East Wing, former First Lady Jill Biden wrote that serving one term had been considered.

'During the 2020 race, Joe had privately floated the idea of being a one-term, transitional President, but as he explored the question of a reelection bid, every one of his senior advisors insisted he needed to run,' she wrote.  

She noted how there had been 'buzz' around potential Democratic primary candidates, 'but we were told that based on polling, Joe was the Democrats' best bet.' 

Dr Biden added: 'While the age question was there, Joe kept showing that he was still able to do the job.'  

Polling even in the late months of 2023 showed that a majority of Americans were concerned about Biden's age should he win a second term. 

That number spiked after Biden tanked in the debate. 

Still, both the former President and First Lady have said Biden would have been victorious over Trump had he stayed in the race. 

But when Dr Biden was asked on Morning Joe whether her husband would have been able to fulfill a second term, she answered, 'I don't know. I don't know the answer to that.'