Joe Biden, who was US vice President under Barack Obama, has officially launched a bid for the White House for the 2020 election online with a video drawing a stark contrast with incumbent Donald Trump.
A moderate who has made his appeal to working-class voters who deserted the Democrats in 2016 a key part of his political identity, Mr Biden launched his bid for the Democratic Party nomination on Thursday as its instant frontrunner in a packed field of 20 contenders.
He announced the third presidential bid of his career by video on YouTube and other social media, saying the contest against Mr Trump was a fight for the future of American democracy.
In his announcement on Thursday, Mr Biden held up the example of the August 2017 attack at a white nationalist rally in Charlottesville, Virginia, that killed a female counterprotester as a defining moment for the nation.
"It was there ... we saw (Ku Klux) Klansmen and white supremacists and neo-Nazis come out in the open ... bearing the fangs of racism," Mr Biden said, criticizing Mr Trump's remarks at the time that there were "very fine people on both sides."
There was no moral equivalence between racists and those fighting such inequality, he said.
"We are in the battle for the soul of this nation," he said. "I believe history will look back on four years of this president and all he embraces as an aberrant moment in time. But if we give Donald Trump eight years in the White House, he will forever and fundamentally alter the character of this nation, who we are, and I cannot stand by and let that happen."
Mr Trump responded in a post on Twitter, slamming Biden's "intelligence" and vowing to meet him "at the Starting Gate" if the Democrat wins his party's "nasty" nomination fight.
Mr Biden, 76, had been wrestling for months over whether to run. His candidacy will face numerous questions, including whether he is too old and too centrist for a Democratic Party yearning for fresh faces and increasingly propelled by its more vocal liberal wing.
Critics say his standing in polls is largely a function of name recognition for the former US senator from Delaware, whose more than four decades in public service includes eight years as President Barack Obama's No. 2 in the White House.
Mr Obama's spokeswoman Katie Hill said in a statement that he had long said selecting Mr Biden to be his running mate in 2008 was one of the best decisions he ever made. The statement fell short of a formal endorsement, but said Mr Obama relied on Mr Biden's insight, knowledge and judgment through both election campaigns and his entire presidency.
Mr Biden will travel across the country in the coming weeks to detail his plans to rebuild the middle class, kicking off his tour with a visit on Monday to Pittsburgh, his campaign said.
Known for his verbal gaffes on the campaign trail, Mr Biden failed to gain traction with voters during his previous runs in 1988 and 2008. He dropped his 1988 bid amid allegations he had plagiarized some of his stump oratory and early academic work, but his experience and strong debate performances in 2008 were what impressed Mr Obama to select him as a running mate.
Biden decided against a 2016 presidential bid after a lengthy public period of indecision following the death of his son Beau of brain cancer in May 2015. Beau had urged him to run. Biden faces similar family considerations this time around as he continues to cope with Beau's demise, while his other son, Hunter, has gone through a divorce.
20 Democrats seeking nomination
The diverse group of 20 vying to challenge President Donald Trump, the likely Republican nominee, includes six US senators. A record six women are running, as well as black, Hispanic and openly gay candidates who would make history if one of them becomes the party's nominee. Here are the Democrats who have launched campaigns, listed in order of their RealClearPolitics national polling average for those who register in opinion surveys.
- Joe Biden: The leader in polls of Democratic presidential contenders, the 76-year-old is the second-oldest candidate in the nominating contest after Bernie Sanders. Mr Biden relishes his "Middle-Class Joe" nickname and touts his working-class roots. He was recently the subject of allegations of unwanted physical contact with women, and pledged to be "more mindful" of respecting "personal space" in an attempt to tamp down the controversy.
- Bernie Sanders: The senator from Vermont lost the Democratic nomination in 2016 to Hillary Clinton but has jumped in for a second try. The 77-year-old will have to fight to stand out in a packed field of progressives touting issues he brought into the Democratic Party mainstream four years ago. His proposals include free tuition at public colleges, a $15 minimum wage and universal healthcare. He benefits from strong name recognition and a robust network of small-dollar donors, helping him to raise $5.9 million during his first day in the contest. Sanders, whose father was a Jewish immigrant from Poland, has shown a more personal side in this campaign, highlighting his struggles while growing up in a working-class family. He also has tried to reach out to black and Hispanic leaders after having trouble winning over minority voters in 2016.
- Beto O'Rourke: The former three-term Texas congressman has been jumping on to store countertops ever since to deliver his optimistic message to voters in early primary states. O'Rourke, 46, gained fame last year for his record fundraising and ability to draw crowds ahead of his unexpectedly narrow loss in the U.S. Senate race against Republican incumbent Ted Cruz. O'Rourke announced a $6.1 million fundraising haul for the first 24 hours of his campaign, besting his Democratic opponents. But with progressive policies and diversity at the forefront of the party's nominating battle, O'Rourke will face a challenge as a wealthy white man who is more moderate on several key issues than many of his competitors.
- Kamala Harris: The first-term senator from California would make history as the first black woman to gain the nomination. The 54-year-old daughter of Jamaican and Indian migrants, announced her candidacy on the holiday honoring slain civil rights leader Martin Luther King Jr. She has made a quick impact in a Democratic race that will be heavily influenced by women and minority voters. She raised $1.5 million in the first 24 hours of her campaign and drew record ratings on a CNN televised town hall. She supports a middle-class tax credit, Medicare for All healthcare funding reform, the Green New Deal and the legalization of marijuana. Her track record as San Francisco's district attorney and California's attorney general has drawn scrutiny in a Democratic Party that has shifted in recent years on criminal justice issues.
- Pete Buttigieg:The 37-year-old mayor of South Bend, Indiana, is emerging from underdog status as he begins to build momentum with young voters. A Harvard University graduate and Rhodes Scholar at the University of Oxford, he speaks seven languages and served in Afghanistan with the US Navy Reserve. He touts himself as representing a new generation of leadership needed to combat Trump. Buttigieg would be the first openly gay presidential nominee of a major American political party.
- Elizabeth Warren: The 69-year-old senator from Massachusetts is a leader of the party's liberals and a fierce Wall Street critic who was instrumental in creating the Consumer Financial Protection Bureau. She has focused her presidential campaign on her populist economic message, promising to fight what she calls a rigged economic system that favors the wealthy. She also has proposed eliminating the Electoral College, vowed to break up Amazon, Google and Facebook if elected, and sworn off political fundraising events to collect cash for her bid. Warren apologized earlier this year to the Cherokee Nation for taking a DNA test to prove her claims to Native American ancestry, an assertion that has prompted Mr Trump to mockingly refer to her as "Pocahontas".
- Cory Booker: The 49-year-old New Jersey senator and former mayor of Newark gained national prominence in the fight over Brett Kavanaugh's Supreme Court nomination. Booker, who is black, has made US race relations and racial disparities a focus of his campaign, noting the impact of discrimination on his family. He embraces progressive positions on Medicare coverage for every American, the Green New Deal and other key issues, and touts his style of positivity over attacks. Booker eats a vegan diet and recently confirmed rumors he is dating actress Rosario Dawson.
- Amy Klobuchar: The third-term senator from Minnesota was the first moderate in the Democratic field vying to challenge Mr Trump. Age 58, she gained national attention in 2018 when she sparred with Brett Kavanaugh during Senate hearings for his Supreme Court nomination. On the campaign trail, the former prosecutor and corporate attorney supports an alternative to traditional Medicare healthcare funding and is taking a hard stance against rising prescription drug prices. Her campaign reported raising more than $1 million in its first 48 hours. Her campaign announcement came amid news reports that staff in her Senate office were asked to do menial tasks, making it difficult to hire high-level campaign strategists.
- Julian Castro: The secretary of housing and urban development under President Barack Obama would be the first Hispanic to win a major US party's presidential nomination. Age 44, his grandmother migrated to Texas from Mexico and he has used his family's personal story to criticise Mr Trump's border policies. He advocates a universal pre-kindergarten program, supports Medicare for All and cites his experience to push for affordable housing. He announced his bid in his hometown of San Antonio, where he once served as mayor and a city councilman. His twin brother, Joaquin Castro, is a Democratic congressman from Texas.
- Andrew Yang: The entrepreneur and former tech executive is focusing his campaign on an ambitious universal income plan. Mr Yang, 44, wants to guarantee all American citizens between the ages of 18 and 64 a $1000 check every month. The son of immigrants from Taiwan, Yang also is pushing for Medicare for All and proposing a new form of capitalism that is human-centered. He lives in New York.
- Kirsten Gillibrand: Known as a moderate when she served as a congresswoman from upstate New York, she has refashioned herself into a staunch progressive calling for strict gun laws and supporting the Green New Deal. The New York senator, 52, has led efforts to address sexual assault in the military and on college campuses, and pushed for Congress to improve its own handling of sexual misconduct allegations. On the campaign trail, she has made fiery denunciations of Mr Trump. She released her tax returns for the years 2007 through 2018, offering the most comprehensive look to date at the finances of a 2020 White House candidate, and has called on her rivals to do the same.
- John Hickenlooper: The 67-year-old former Colorado governor has positioned himself as a centrist and an experienced officeholder with business experience. He is the only Democratic presidential candidate so far to oppose the Green New Deal plan to tackle climate change, saying it would give the government too much power in investment decisions. During his two terms in office, Colorado's economy soared and the Western state expanded healthcare, passed a gun control law and legalised marijuana. The former geologist and brew pub owner is among the many candidates who have refused to take corporate money.
- Jay Inslee: The Washington state governor has moved to put a moratorium on capital punishment and fully implement the Affordable Care Act, commonly known as Obamacare, and accompanying expansion of Medicaid health coverage for the poor. Age 68, he has made fighting climate change the central issue of his campaign. He has not settled on a position on Medicare for All but does support the Green New Deal backed by progressives. He spent 15 years in Congress before being elected governor in 2012.
- John Delaney: The former U.S. representative from Maryland became the first Democrat to enter the 2020 race, declaring his candidacy in July 2017. Delaney, 55, plans to focus on advancing only bipartisan bills during the first 100 days of his presidency if elected. He is also pushing for a universal healthcare system, raising the federal minimum wage and passing gun safety legislation.
- Tulsi Gabbard: The Samoan-American congresswoman from Hawaii and Iraq war veteran is the first Hindu to serve in the US House of Representatives. After working for her father's anti-gay advocacy group and drafting relevant legislation, she was forced to apologize for her past views on same-sex marriage. The 37-year-old has been against US intervention in Syria and slammed Mr Trump for standing by Saudi Arabia after the murder of journalist Jamal Khashoggi. She endorsed Bernie Sanders during his 2016 presidential campaign.
- Eric Swalwell: The third-term congressman from a California district south of San Francisco cited tackling student debt and gun violence among the reasons he jumped into the Democratic primary race. Swalwell, 38, is among the younger candidates vying for the 2020 Democratic nomination. He served on the House Intelligence Committee and founded the Future Forum, a group of more than 25 Democratic lawmakers that visits universities and community colleges to discuss issues important to millennial voters like student loan debt and climate change.
- Tim Ryan: The moderate nine-term congressman from a working-class district in the battleground state of Ohio has touted his appeal to the blue-collar voters who fled to Mr Trump in 2016. He says Mr Trump has turned his back on those voters and failed to live up his promise to revitalize the manufacturing industry. Age 45, he pledges to create jobs in new technologies and to focus on public education and access to affordable healthcare. He first gained national attention when he unsuccessfully tried to unseat Nancy Pelosi as the House Democratic leader in 2016, arguing it was time for new leadership. A former college football player, he also has written books on meditation and healthy eating.
- Seth Moulton: An Iraq War veteran and member of Congress, the 40-year-old was first elected to the House of Representatives in 2014 when he defeated a fellow Democrat in the primary election. He served in the Marines from 2001 to 2008 and became a vocal critic of the Iraq War in which he served, saying no more troops should be deployed to the country. He has advocated stricter gun laws saying military-style weapons should not be owned by civilians. Moulton supports the legalization of marijuana and told Boston public radio station WGBH in 2016 that he had smoked pot while in college. After Democrats took control of the House of Representatives in 2018, Moulton helped organize opposition to Representative Nancy Pelosi's bid to again become speaker.
- Marianne Williamson: The 66-year-old New York Times best-selling author, motivational speaker and Texas native believes her spirituality-focused campaign can heal America. A 1992 interview on Oprah Winfrey's show propelled Williamson to make a name for herself as a "spiritual guide" for Hollywood and a self-help expert. She is calling for $100 billion in reparations for slavery over 10 years, gun control, education reform and equal rights for lesbian and gay communities. In 2014, she made an unsuccessful bid for a House seat in California as an independent.
- Wayne Messam: The 44-year-old defeated a 16-year incumbent in 2015 to become the first black mayor of the Miami suburb of Miramar. He was re-elected in March. The son of Jamaican immigrants, he played on Florida State University's 1993 national championship football team, and then started a construction business with his wife. He has pledged to focus on reducing gun violence, mitigating climate change and reducing student loan debt and the cost of healthcare.