Barack Obama's former Vice President Joe Biden has formally entered the 2020 race for US President, betting his working-class appeal will help him overcome questions about his place in today's increasingly liberal Democratic Party.
He made his announcement in a video posted on Twitter, declaring: "We are in the battle for the soul of this nation."
"If we give Donald Trump eight years in the White House, he will forever and fundamentally alter the character of this nation," Mr Biden said.
US Vice President Joe Biden laughs as President Barack Obama speaks in 2017. Source: AFP
"Who we are. And I cannot stand by and watch that happen."
Thursday's announcement marks the unofficial end of the chaotic early phase of the 2020 presidential season. The field now features at least 20 Democrats jockeying for the chance to take on President Trump next year.
Mr Biden, a 76-year-old lifelong politician, becomes an instant frontrunner alongside Vermont Senator Bernie Sanders, who is leading many polls.
Among Democrats, Mr Biden has unmatched international and legislative experience and he is among the best-known faces in US politics.
But the anti-establishment wave that swept President Trump into office has not been kind to either party's statesmen. Mr Biden's team worries about his fundraising ability and his tendency to commit gaffes. His centrist approach in a party moving left on major policy debates raises questions about his appeal.
Four years Mr Trump's senior, Mr Biden would be the oldest person ever elected president should he win. Yet his allies believe the sceptics will ultimately warm to his strong connections to the Obama years.
Barack Obama gives a tribute to Joe Biden in 2017. Source: AFP
Mr Biden has said he would campaign as an "Obama-Biden Democrat," who is as pragmatic as he is progressive. He's aiming to be a conduit between working-class white voters and the younger, more diverse voters who backed Mr Obama.
The Republican Party wasted no time seeking to undercut Mr Biden's record, releasing a video on Wednesday questioning economic growth under Mr Obama and Mr Biden while resurrecting conservative arguments against their health care law and a failed investment in green energy company Solyndra.
Yet privately, Trump allies have warned that the former Vice President might be the biggest re-election threat given his potential appeal among the white working class in the Midwest, the region that gave Mr Trump a path to the presidency.
Joe Biden speaks at a workers rally last week. Source: Getty Images
With a record that stretches half a century, Mr Biden's challenges are easy to find.
Most recently, he struggled to respond to claims that he touched 2014 Nevada lieutenant governor nominee Lucy Flores' shoulders and kissed the back of her head before a fall campaign event. A handful of other women have made similar claims, though none has alleged sexual misconduct.
Mr Biden later pledged in an online video to be "much more mindful" of respecting personal space but joked two days later that he "had permission" to hug a male union leader before addressing the group's national conference.
The episode offered a stark reminder of Mr Biden's proclivity to gaffes and his long record in public office that has never felt the full glare of the spotlight that comes along with being a presidential frontrunner.
His first White House bid in 1988 ended after a plagiarism scandal. He dropped out of the 2008 race after earning less than one per cent of the vote in the Iowa caucuses. Later that year, Mr Obama named Mr Biden as his running mate.
