Joe Biden and more: These are the candidates vying for the 2020 Democratic presidential nomination

With an unpopular incumbent Republican in the White House, and no clear favourite for the Democratic nomination, the contest is wide open.

So far, 21 serious (or semi-serious) candidates have announced they are running The official debates begin in June, with the first caucus in Iowa in February of next year.

The field of candidates is set to make history for its diversity, with more women and visible minorities than any contest before.

Michael Bennet

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Mr. Bennet is “leaning in,” as they say, to his relative lack of profile. “You probably don’t know me because I don’t go on cable news every night,” the Colorado senator says in his campaign launch video. “I didn’t go to Washington to get attention, I went to pay attention.” He is trying to position himself as a moderate who can get things done, pledging to create a government health insurance program that Americans can opt into without getting rid of private health care; a tax cut; and new ethics rules banning former members of Congress from becoming lobbyists.

Joe Biden

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Mr. Biden opens this third bid for the presidency leading every poll. A career politician who spent 36 years in the senate and eight as Barack Obama’s vice-president, Mr. Biden will lean on his experience and moderate reputation to argue that he can build a big-tent coalition.

His avuncular, if gaffe-prone, persona is often seen as relatable, particularly among older and more moderate Democrats in the Rust Belt swing states that handed Mr. Trump the presidency. A native of blue-collar Scranton, Pennsylvania, Mr. Biden has long successfully traded on the every-man elements of his personal narrative: His father losing his job and moving the family to Delaware in search of better economic opportunities; his daily train commutes home during his early years in the Senate as he worked to raised his sons as a single father.

But Mr. Biden’s age (76), relative centrism and long years as a Washington insider could work against him. The Democrats are moving left and will want to turn out younger voters in larger numbers to win next year.

He has also vowed to change his behaviour after women said he invaded their personal space by squeezing their shoulders, smelling their hair and pressing his forehead to theirs during public events. As well, Mr. Biden has faced persistent criticism for his handling of the 1991 Senate confirmation of Supreme Court Justice Clarence Thomas. As the then-chair of the Senate Judiciary Committee, Mr. Biden allowed a hearing with Anita Hill, who accused Mr. Thomas of sexual harassment, to turn into an aggressive grilling of Ms. Hill, and then did not call as witnesses other women who also accused Mr. Thomas of inappropriate conduct.

Cory Booker

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Mr. Booker shot to national fame as the cool-guy mayor of Newark, N.J., overseeing a renaissance of his city’s downtown and personally fielding requests for municipal services on social media. Look for him to trade heavily on this image in the primaries (his introductory campaign video shows him strolling around his neighbourhood, shouting “wassup?” to passersby.) But his mixed record in city politics could also cause trouble: Mr. Booker’s tenure has regularly been criticized for making mostly cosmetic changes to Newark that didn’t effectively deal with underlying problems of poverty and unemployment.

A senator since 2013, Mr. Booker is also an Ivy-League-trained lawyer who spent a few years working for non-profit social-justice groups. Standing 6’3” with a well-modulated baritone, Mr. Booker has a stage presence that should stand him in good stead once the long string of crowded campaign debates begin in the spring.

Steve Bullock

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Montana’s two-term Democratic governor is best known for his long-running battles against corporate spending in political campaigns. That focus gives him a distinctive – and, theoretically, bipartisan – issue to run on, even as a lack of name-recognition and late entry to the race are certain to hold him back. Mr. Bullock’s other selling point: Leading a red state, suggesting that there is a path for the Democrats to win over Republican voters with the right candidate.

Pete Buttigieg

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The 37-year-old mayor of South Bend, Ind., is aiming to become the U.S.’s youngest-ever and first openly gay president. A former political staffer and consultant, Mr. Buttigieg is also a naval reservist who did a tour of duty in Afghanistan during his first term as mayor.

Mr. Buttigieg faces long odds, largely because of a lack of name recognition. But surprisingly strong fundraising numbers and a burst of media attention, combined with the unpredictable nature of the country’s presidential politics may give him reason to hope for a breakthrough – or at least boost his profile enough to be named vice-presidential running mate by the eventual nominee.

Julian Castro

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A 44-year-old lawyer from San Antonio, Tex., Mr. Castro served as secretary of housing and urban development during President Barack Obama’s second term. Mr. Castro has promised to overhaul the U.S. immigration system to make it possible for all unauthorized immigrants to obtain citizenship, create a subsidized prekindergarten program similar to one he set up locally while serving as mayor of San Antonio and bring in universal health care. He has an identical twin brother, Congressman Joaquin Castro.

Youthful and Latino, Mr. Castro appeals to two core Democratic constituencies that the party has to do a better job of motivating to get to the polls. Highlighting immigration could also help him stand out in the crowded field. His challenge will be building a national political organization that can help him break into the top tier of candidates.

Bill de Blasio

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The leftist New York mayor has racked up a solid record of policy achievements: A free, universal preschool program; a US$15 minimum wage; and a wide-ranging plan to drive down the city’s carbon emissions.

He has also accumulated a pile of political baggage. Mr. de Blasio has a rocky relationship with the city’s police department, his approval ratings are middling and he has a knack for bad optics – showing up late to events, for instance, or insisting that he be chauffeured daily from the mayoral mansion in Manhattan to his favourite YMCA in Brooklyn.

Mr. de Blasio is so far playing up his status ruling Mr. Trump’s hometown, even as other candidates avoid putting the President at the centre of their own campaigns. “I’m a New Yorker. I’ve known Trump is a bully for long time,” Mr. de Blasio says in his launch video. “Don’t back down in the face of the bully. Confront him. Take him on.”

John Delaney

The former congressman from Maryland was the first Democrat to declare his candidacy, more than three years before the election. But his head start has not resulted in a surge of popularity or exposure: He is so obscure, many U.S. polls haven’t bothered including him. The few that have, show him struggling to crack a single percentage point.

Tulsi Gabbard

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Ms. Gabbard was first elected to Hawaii’s legislature at the age of 21, and has spent the last six years in the U.S. House of Representatives. In between, she served in the National Guard, including a tour of duty in Iraq.

Ms. Gabbard’s challenge will be generating attention against higher-profile candidates. She has also drawn criticism for helping her father, a Hawaii state senator, run a campaign against same-sex marriage in the state in the 1990s and early 2000s, and making homophobic comments at the time. Ms. Gabbard issued an apology last week, saying her views on LGBTQ issues have completely changed since then.

Kirsten Gillibrand

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During her decade in the Senate, Ms. Gillibrand has become known for successfully pushing for the repeal of the “don’t ask, don’t tell” policy that prohibited LGBTQ people from serving openly in the military, fighting against sexual misconduct and calling for the abolition of Immigration and Customs Enforcement, the agency that deports undocumented immigrants.

Ms. Gillibrand could face a bumpy ride from the base for her positions on immigration and gun control while serving as a congresswoman for a conservative upstate New York district in the 2000s: She voted to cut federal funds to sanctuary cities and make it easier to hunt, for instance. Her work as a lawyer for tobacco company Philip Morris in the 1990s could also hamper her campaign.

Mike Gravel

His chance of winning the nomination is slim, but Mr. Gravel has certainly won the competition for weirdest campaign launch video: A montage of other Democratic contenders giving speeches with a ghostly image of Mr. Gravel’s stern, disdainful face superimposed in the background. A senator for Alaska in the 1970s, Mr. Gravel has subsequently been an unsuccessful businessman and activist for a proposal to allow U.S. citizens to propose laws that would be put to national referendum if enough people petition for them.

Kamala Harris

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A centrist first-term senator and former California attorney-general, Ms. Harris was a career prosecutor before getting into politics. She also has a Canadian connection: Ms. Harris spent her adolescence in Montreal, where her mother was a professor at McGill. Ms. Harris graduated from Westmount High School, whose alumni include Leonard Cohen and Moshe Safdie. Not that she was particularly enthralled with the bohemian metropolis, at least at first. “I was 12 years old, and the thought of moving away from sunny California in February, in the middle of the school year, to a French-speaking foreign city covered in 12 feet of snow was distressing, to say the least,” she recounts in her autobiography.

Ms. Harris’s legal background has made her effective in the Senate. But it could also come back to haunt her campaign in a party whose base is clamouring for criminal justice reform. Despite being personally against the death penalty, for instance, Ms. Harris fought a court decision that ruled the statute unconstitutional. And she opposed efforts to oblige the attorney-general’s office to investigate instances of police killing people.

John Hickenlooper

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Mr. Hickenlooper is leaning on his executive experience as Denver mayor and Colorado governor – redeveloping downtown, dealing with natural disasters, toughening gun control laws - to stand out in a group full of legislators. Hailing from a swing state, and having dealt with a Republican-controlled state senate at times during his terms as governor, the 67-year-old is effectively pitching himself as a political pragmatist.

His small business background (he ran a brewpub before getting into politics) and dorky-dad mien could play well with middle-class suburban swing voters. But it could also prove overly milquetoast for a party base in search of an exciting leader.

One of Mr. Hickenlooper’s formative experiences, as recounted in a 2017 meeting with Prime Minister Justin Trudeau, involved travelling across Canada: He hitchhiked from Vermont to Montreal with two dogs in tow, then took a train to Vancouver. “It’s almost like I was a calf, and someone put a brand on me,” he recounted. “It’s the first time I ever really saw wilderness…it was all these magical names and magical places.”

Jay Inslee

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Mr. Inslee is focusing his presidential campaign on fighting climate change, promising to launch a transition to 100-per-cent clean energy. The plan, which he compares to John F. Kennedy’s moonshot, is meant in part to differentiate himself in a crowded field by picking an easily identifiable top priority. It also earned him an endorsement from Bill Nye, the television science personality who has found new fame with viral videos taking down climate-change deniers.

On his second term as governor of Washington state, the 68-year-old Mr. Inslee is far from a national figure. He did, however, gain some attention for leading one of the lawsuits that temporarily suspended Mr. Trump’s travel ban. He also tried unsuccessfully last year to impose a carbon price on big polluters in his state.

Amy Klobuchar

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Ms. Klobuchar has cultivated the “Minnesota nice” stereotype of her home state, projecting a folksy public persona and earning a reputation for bipartisan cooperation during her three terms in the Senate. She has been a skilled legislator, sponsoring more successful bills in the last Congress than any other senator.

The former prosecutor hails from the party’s moderate wing; she’s shied away from embracing single-payer healthcare, for instance. While this may be an asset in winning over independent voters, it could work against her with a Democratic base that has moved steadily left in recent years.

Also working against her: A parade of former staffers who say Ms. Klobuchar frequently berates her aides in private, throws papers around her office when she gets upset and makes her staff come to her house and wash her dishes.

Wayne Messam

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Mayor of the Miami suburb of Miramar, Mr. Messam is a small businessman (he owns a construction company) and former college football hero (he played on the 1993 national championship Florida State team.) Mr. Messam also benefits from a compelling personal story: he is the son of a Jamaican immigrant who cut sugar cane by hand during his early years in Florida.

Seth Moulton

He is a 40-year-old Marine Corps captain and Iraq War veteran and a three-term Massachusetts congressman who plotted to overthrow Speaker Nancy Pelosi earlier this year. Mr. Moulton’s campaign is highlighting national security, gun control and the environment.

Beto O’Rourke

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Mr. O’Rourke so worries Republicans that one group ran attack ads against him before he had even launched his presidential campaign. They have good reason to fret: The former congressman from the Texas borderlands came within two percentage points of unseating Senator Ted Cruz in the solidly red state last fall, based mostly on the strength of personal charisma. On the policy front, Mr. O’Rourke has largely defined himself by his positions on immigration, calling for a way for unauthorized immigrants to eventually receive U.S. citizenship. He is on the moderate wing of the party, calling for universal health insurance coverage, for instance, while steering clear of explicitly endorsing a single, government-run system.

Mr. O’Rourke’s signature is direct communication with his large fanbase: He has livestreamed everything from air drumming to Baba O’Riley at a fast-food drive-through to getting his teeth cleaned. But these moments have often read as navel-gazing and can reveal an uncomfortable smugness. In January, when Mr. O’Rourke documented a solo road trip in a series of Jack Kerouac-inspired blog posts, CNN excoriated the “white male privilege” inherent in a middle-aged man leaving his family for a couple of weeks to very publicly try to find himself.

Tim Ryan

Mr. Ryan has been a congressman for Ohio since 2003, representing a swath of the Rust Belt that has been battered by the decline of the manufacturing sector, including the recent closure of Lordstown’s General Motors plant. On the campaign trail, Mr. Ryan is hoping a moderate image will help win back blue collar voters that broke for Mr. Trump in 2016. On Capitol Hill, he is best known for unsuccessfully challenging Nancy Pelosi for leadership of the Democratic House caucus in 2016.

Bernie Sanders

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It’s a testament to the strength of Mr. Sanders’ previous run that most of his pledges – universal health care, free university tuition, paid parental leave, tighter rules for banks and other large corporations – have moved from the margins of American politics to the mainstream of the Democratic Party. But Mr. Sanders may be a victim of his own success: With no shortage of candidates championing his policies, Democratic voters may give the aging hippie a miss in favour of someone younger. Mr. Sanders’ previous run also left a bad taste for some Democrats, not least because of the “Bernie bros” – overzealous and often belligerent male supporters of the Senator who took to flaming Clinton supporters on social media.

Mr. Sanders has spent most of his adult life in politics, with stints as mayor of Burlington, Vermont and in the House of Representatives before winning a Senate seat in 2007.

Eric Swalwell

Rounding out the babyface brigade is this 38-year-old congressman, who represents a district in the San Francisco Bay area. Mr. Swalwell is on his fourth term, and is best known for pushing for gun control. Bonus point: He was born in Iowa, the first state to vote in the presidential nominating contest next year, and is playing up his local roots in his campaign.

Elizabeth Warren

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In her seven years representing Massachusetts in the Senate, the former law professor has established herself as a leader of her party’s left. Best known for championing tougher regulation of the country’s banks, she also backs universal healthcare, cheaper student loans and a “wealth tax” on the richest Americans. Ms. Warren opposes the overhauled NAFTA – or U.S.-Canada-Mexico Agreement – because she argues it does not do enough to stop American manufacturing leaving the country.

Her skill at delivering a populist message – particularly when railing against the excesses of the financial industry – has delivered her a loyal following in a party whose appetite for a more aggressive policy agenda appears to be growing. It also sets her on a collision course with her Senate colleague Bernie Sanders, who is running pretty much the exact same messaging, as the two battle to become the standard-bearer for the left.

Ms. Warren has also faced accusations of cultural appropriation for referring to herself as “Native American” and “Cherokee” despite having no affiliation with any Indigenous nation and being unable to identify any Indigenous ancestors. She only complicated matters last year by trying to use a DNA test to validate her claim.

Marianne Williamson

A California self-help author, Ms. Williamson is hoping to repeat Mr. Trump’s feat of winning the big job in the White House without holding any previous office.

Andrew Yang

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He’s a serial entrepreneur who has never held elected office, but Mr. Yang has won a devoted online following with warnings that the U.S. isn’t prepared for the rise of automation. His proposed solution is a universal basic income, specifically a monthly $1,000 payment to every American, meant to blunt the effect of this transition. Whether he can translate his crew of meme-loving fanboys into any real-world support remains to be seen.