Joe Biden has tried to become president for three decades. That dream is now a reality.

He had what it takes to win – but does he have the stamina for four years in the White House?

He will be America’s oldest president, aged 78, by the time of his inauguration.

He has been knocking around American politics for half a century, his political career beginning when Richard Nixon was in the White House and America was still sending men to the moon. But this is one candidate for whom age may be an asset.

In his long life, Mr Biden has suffered personal loss more than most and supporters say that has given him an empathy for a nation suffering the pain and grief of the COVID-19 pandemic.

Friends say Mr Biden’s strength of character and decency is what America needs in these extraordinary times, and that will help him prevail over his turbulent rival.

He became the fifth youngest senator in US history in 1972. A few weeks later tragedy struck the Biden family. He lost his wife Neilia and one-year-old daughter Naomi in a car crash that also left their two sons, Hunter and Beau badly injured.

His ability to rise above that tragedy is well known by Americans. He was determined to see his boys every night, taking the hour and a half train journey from Delaware to Washington DC at the start and end of each day to say goodnight to them.

When others might have fallen apart, Mr Biden found the strength to carry on both then and when ill health and more tragedy struck later in his troubled life.

He suffered multiple aneurysms in 1988, surviving one nine-hour operation to save his life.

Then in 2015 one of those two boys he was so devoted to, Beau, died of brain cancer aged 46. Biden’s grief was one reason why he chose not to run against Mr Trump.

He has said how his father frequently said: “Champ, the measure of a man is not how often he is knocked down, but how quickly he gets up.”

But there is also a sense of fatalism about Mr Biden. He is quoted as saying he believes that life balances out peoples’ suffering and fortune – “the bigger the highs, the deeper the troughs”.

He had seemed to be heading for another trough at the start of this year as his campaign to become the Democratic presidential contender began to flounder.

He had entered it the front-runner as a former vice president, but by February the campaign’s wheels were spinning and the candidate was sometimes lost for words and almost doddery on the trail.

But then Mr Biden’s fortunes turned again. Having looked in serious trouble in Iowa, he seized victory a month later in South Carolina setting himself on the path to victory.

The fiercely contested primary season has tested Mr Biden. He has been accused of “handsiness” or a tendency to invade women’s personal space and there is plenty of awkward footage making the point.

His friends and supporters say his tactility springs from his warmth and empathy. But during the campaign he was forced to admit his behaviour was no longer appropriate.

In a video statement he told voters, “I get it, the boundaries of personal space have been changed”. He has also denied accusations by former Senate staffer Tara Reade that he sexually assaulted her in 1993.

The woman who is now his running mate, Kamala Harris, criticised his support for segregationists early in his career when he joined them opposing school bussing to racially integrate schools.

And his drafting of the 1994 crime bill that led to mass incarcerations, lengthy jail sentences and the proliferation of more and more prisons has dogged his political career ever since.

Mr Biden can have a clumsiness with words while at the same time being an accomplished debater. His gaffes or “Bidenisms” are legendary and he has appeared at times decidedly out of touch.

The jury is out as to whether they have weakened him among voters or endeared him in this election.

He has borrowed words too. Most notoriously in 1988 when he plagiarised a speech by Neil Kinnock word for word. To be fair he had credited the former British Labour leader on previous occasions but at least once seemed to present the words as his own.

But he was able to play on the strengths of a lifetime in public service to rout his Democrat rivals and present himself as the competent alternative to President Trump, a seasoned steady hand on the wheel in a time of plague and chaos.

Eight years as vice president allows Mr Biden to claim Barack Obama’s successes as his own both at home and abroad.

Those who know him from those years say it’s his length of service and what he’s gained from it that makes him stands out as a potential president.

Sir Peter Westmacott, who was British ambassador to the US during the Obama years, told Sky News: “He’s old for a presidential candidate, that’s for sure.

“But he’s hugely experienced. He’s got an extraordinary wide range of contacts around the world. He does know a great deal and cares a lot about different countries that he’s got to know.

“He will be a man who understands that in many areas he needs to have young capable people to who he can delegate rather than try to do it all himself. I don’t think he’ll have any illusion about that.”

The length of Mr Biden’s career has won him support in demographics that could be key to victory in this election. His close relationship with America’s first black president has further cemented his support among African Americans.

He sees himself as the champion of the blue-collar white voter and hopes that will give him an edge as he tries to gnaw away at Donald Trump’s base.

He will need to maintain the support of ardent Democrats and engage the backing of others who have drifted away from his party or even moderate Republicans disaffected by the Trump presidency.

Mr Biden’s pitch is to restore and build on Mr Obama’s legacy and unite a divided country after the turmoil of the Trump years.

If the voters buy it what kind of president can we expect?

His first priority will be dealing with the COVID-19 pandemic. He has been sharply critical of Mr Trump’s handling of the virus.

A Biden presidency will need to sort out the testing debacle and control the virus sufficiently to allow the US economy to break free from lockdown.

His supporters warn against assuming his presidency will be simply a restoration to the Obama era, just a correction from the Trumpian aberration.

Those advising him on economic policy say it will be radical, almost Rooseveltian in terms of spending and investment both to overcome the impact of COVID-19 and deal with climate change.

He wants to spend $2trn putting America on the path to eliminating carbon emissions by mid-century.

Given his family’s tragic history and his own brush with death, it is no surprise that Mr Biden is placing a lot of emphasis on health.

As he put it in an early TV ad, healthcare is “personal” to him. He hopes to reinforce Mr Obama’s reforms to healthcare but stops short of the “healthcare for all” proposals advocated by his former Democrat rival Bernie Sanders and others on the more progressive wing of his party.

On the world stage a President Biden is likely to try and restore America’s place at the centre of the multilateral rules based world order that the US has led since World War II after the years of President Trump’s more isolationist economic nationalism.

As a former vice president and chair of the Senate foreign relations committee, he is a firm believer in the Pax Americana and has spoken out against the damage he says Mr Trump has done to America’s standing in the world.

His challenges on that world stage will be considerable. The world has moved on since he was vice president.

China has grown in power and tensions have increased between the two super powers. Europe is not the same since Brexit and the rise of populist parties.

Vladimir Putin has become increasingly meddlesome not least with regards to American democracy.

And the Middle East has changed under President Trump. Mr Trump has moved the US embassy to Jerusalem, discarded the Iranian nuclear deal and brokered a deal normalising relations between Israel, the UAE and Bahrain. How much of that will Mr Biden try and reverse?

Mr Biden harks back to a possibly lost age at home too. He has talked of restoring the spirit of bipartisanship in American politics.

The founding fathers designed a system of government that works only when there is some sense of compromise. That has been lost in the bitterly adversarial politics of both the Obama and Trump years.

Mr Biden says he wants a return to co-operation across the aisle on Capitol Hill to solve America’s pressing problems. If anyone has the experience, charm and friends in both parties to dispel some of the bitter antagonisms of the last two presidencies it may be Mr Biden.

He is betting that Americans want that kind of politics. His Republican opponents may not see it that way.

The Americans will have a choice this November between two very different politicians who both claim to have the common touch, that direct line to the hearts and minds of the ordinary voter.

But while Mr Trump was born into wealth, Mr Biden started life in the blue-collar town of Scranton, northeast Pennsylvania, the son of a used car salesman.

His hardscrabble beginnings and the challenges of a tragic life have given him a tough strength of character and sense of decency say those who know him well.

Campaign officials say they try and put him on the phone with an ordinary voter every day in calls that often overrun as he offers advice and solace.

He may not be known for soaring oratory but words to comfort and console a grieving nation will come to him more easily than most.

His rival calls him sleepy and slow. His friends decent and full of humanity. There is none of the excitement offered by Mr Trump or the hope and change inspiration promised by Mr Obama.

But that may not be what many voters are looking for now.

They may settle for a slower pace at the White House if it brings with it the competence and wisdom of a veteran of half a century in politics and public service.

The polls currently point in that direction. But the last leg of this race will be the most challenging and the going will be rough and nasty.

Friends say Mr Biden has a resilience that goes goes back to his tough upbringing and the trials of his life.

His opponent is a street fighter who observes none of the rules of politics and this election is already the roughest America has ever known.

At the age of 77 Mr Biden will need all the strength of character he can muster if he wants to fulfil his dream.