Joe Biden has wanted to be president for at least 30 years. He first ran in 1988, crashing out in his bid for the Democratic nomination over a plagiarism scandal.
In 2008, Mr Biden took on Barack Obama but again stumbled at the first hurdle, securing less than 1 per cent of the vote at the all-important Iowa caucus.
At the last election it was tragedy that intervened, with the then-vice president declining to run after his son Beau’s death from cancer.
Now, with Mr Biden the presumptive Democratic presidential nominee, one question looms large – is 2020 the year Mr Biden finally gets over the line?
Fuelling his thinking, according to Larry Rusky, his communications director for both the ’88 and ’08 presidential bids, is a concern for where the country is heading under Donald Trump.
“Joe Biden has always believed in public service as a noble profession. I think it galls him immensely that Trump and others have tried to taint that," Mr Rusky told The Telegraph.
“To the extent that he is driven, he’s driven by a need to contribute to the relationship between the government and its people.”
The appeal of Mr Biden in the Age of Trump is clear, in the eyes of supporters. A senator for 36 years and a vice president for eight, he has the experience and authority that Mr Trump lacks.
His record of deal-making, from helping pass an assault weapons ban while Senate judiciary committee chairman to negotiating Ukrainian ceasefires and budget deals as vice-president, shows a bipartisanship lacking in the current White House.
Plus his uplifting rhetoric, inspiring back-story and Pennsylvanian roots prove he can win back the blue collar voters who flocked to Mr Trump at the last election.
That is certainly what Mr Biden thinks, according to his recent memoir. He spelled out how his 2016 campaign would have been pitched around winning back the middle class – where Mr Trump did so well.
His supporters argue that Mr Biden has enough centrist clout to win back Trump voters while possessing sufficient left-wing credentials from the Obama years to inspire the Democratic base.
And it’s not just backers. “Eighty per cent of people I talk to on the Hill, both Republicans and Democrats, say Joe Biden has the best chance of beating Trump,” said a UK official whose job it is to know.
Read more: Donald Trump vs Joe Biden policies
But for those hoping Mr Biden is the Democrats’ knight in shining armour, the list of weaknesses to his candidacy is not insubstantial.
There are the gaffes. From asking a wheelchair-bound politician to stand for applause to telling a largely black audience that Mitt Romney wanted to “put y'all back in chains”, he developed a reputation for verbal slips while vice-president.
It even has its own term, Bidenism, defined as a movement which practises “the art of committing public humiliation to themselves and other prominent public officials”.
There is the baggage. In an anti-establishment moment, will US voters really go for the guy who has spent almost half a century at the heart of Washington's "swamp"?
Most recently, a number of women came forward with claims that Mr Biden inappropriately touched them.
In response, Mr Biden released a video in which he said "social norms are changing" and pledged to be “more mindful about respecting personal space in the future".
And then there is age. The former Delaware senator, four years older than Mr Trump, would be 78 on inauguration date if he won – the oldest president ever elected for the first time.
Other concerns abound too. One former aide who worked on Mr Biden’s presidential bids but has since become disillusioned paints a downbeat picture of his former boss.
“I feel the media loves the soap opera of Joe Biden and never looks below the hood,” said the ex-aide, who asked not to be named.
“Does he really have the network, the fundraising base, the talent to put forward a [successful] presidential bid?”
The source went on: “There is nothing to prove he can win Pennsylvania and Ohio over any other candidate.”
His VP pick
Mr Biden has picked Kamala Harris as his running mate. The first ever black woman to be formally named on a major party's presidential ticket, Ms Harris is moderate, popular with the party's establishment, and has plenty of Washington experience. She is also a senator for California and was the state's attorney-general.
Ms Harris is a skilled campaigner and her centrist policies and record as a prosecutor make her difficult to paint as a radical Democrat who is weak on crime, no matter how hard the Trump campaign will try.
As a biracial woman, Ms Harris also gives legitimacy to Mr Biden's assurance that he can enact the sweeping changes many Americans have called for in the wake of the summer's racial inequality protests.
Mr Biden has also enjoyed a campaign funding boost since he announced he was running with Ms Harris, thanks in no small part to her friends and supporters in wealthy California.
But a key battleground for Mr Biden could be trying to win the votes of progressives and the young, who lean more to the left. Ms Harris's background as a prosecutor arguably makes this more difficult: many young Americans and voters on the party's left see her as a "cop" with a history of prosecuting African-Americans rather than an agent of change or racial justice.
Away from politics, Mr Biden's personal tragedies will unavoidably re-enter the spotlight if he runs for the presidency.
On December 18 1972, just weeks after he first won a Senate seat, Mr Biden’s wife Neilia and one-year-old daughter Naomi were killed in a car accident.
Neilia’s car struck a tractor trailer while the family was out Christmas shopping. Mr Biden’s sons, Beau and Hunter, were badly injured but survived the crash. Mr Biden later remarried, having daughter Ashley with his wife Dr Jill Biden in 1981.
In August 2013, tragedy struck again when Beau, by then a politician himself talked of as a future presidential hopeful, was diagnosed with brain cancer. He would die two years later.
During that period, Mr Biden continued his duties as vice president and shared emotional moments with Mr Obama, the man who picked him as a running mate in 2008.
Mr Biden recalls in Promise Me, Dad, his book about those years, how Mr Obama once shed tears for his son and offered to personally pay for the treatment if money was short.
The pair’s relationship, the most significant of Mr Biden’s political career, was so close in public that their “bromance” became a familiar joke before they left office.
However there had been tensions between 2008 and 2016 as their time in the White House switched from achieving in office to planning for what came next.
Mr Biden made little attempt in his memoir to hide his frustration at Mr Obama’s repeated attempts to urge him not to run for the presidency in 2016, believing Ms Clinton was better placed.
Friends and families describe Mr Biden’s upbeat outlook as key to his success. “He’s an optimist, but, you know, not in La-La-Land,” his sister Val Biden Owens has said.
He is a car enthusiast, given a 1967 Corvette Stingray as a wedding gift by his father, and an American football player during his high school and college years.
Mr Rusky, a friend as well as former political aide, suggests that Mr Biden would have carefully weighed up a potential 2020 presidential bid.
“Assuming that the family is settled and he is feeling physically up for it, then it really comes down to doing the political equation,” said Mr Rusky, discussing what will be going through Mr Biden's mind.
“Is his voice welcome in the debate? Is there space in the race? Is there a demand for his participation?”
Mr Rusky said Mr Biden will not let concerns about age to stand in his way.
Once, before the 2012 election campaign, a friend quoted Pope John XXIII about “approaching old age” and suggested he take it easy.
Mr Biden shot back with a quotation of his own, referencing the poet Dylan Thomas: “Do not go gentle into that good night. Rage, rage against the dying of the light.”
Listen to Ben Riley-Smith discuss Joe Biden's chances of winning the US Election with pollster Larry Sabato, Hillary Clinton's former Political Director Amanda Renteria and Joe Biden's former Senior Adviser on The Telegraph's weekly political podcast, Chopper's Politics, on the audio player above.