US election Democratic candidates: Contenders for the primaries and 2020 presidential nomination

The race is on to win the right to challenge Donald Trump for the 2020 presidential election. Only one candidate from a field of two dozen will be named the Democratic Party’s official nominee. The hopefuls have starkly different backgrounds, ideologies, strengths and weaknesses. Who the party picks could determine the country's future. Voting starts in February 2020 with an eventual winner confirmed in July – ready to take on Mr Trump at the election on November 3.

Joe Biden has framed himself as the person best placed to defeat Donald Trump and is the overwhelming favourite in the Democrat field. The 76-year-old, who served as Barack Obama’s vice president for eight years, believes his centrist platform can win back Obama-Trump voters in key swing states.

Elizabeth Warren, a senator for Massachusetts, is vying with Bernie Sanders to represent the progressive left of the Democratic Party. She has condemned the corrupting influence of money on politics and lamented lost economic opportunities for working families. However she has faced criticism over her claims of Native American heritage.

Bernie Sanders, an independent senator for Vermont, blindsided Hillary Clinton with an insurgent campaign from the Left in 2016 which energised young voters in a surge that drew comparisons with Labour leader Jeremy Corbyn. He has a loyal and established network of activists who could be remobilised for his second shot at the Democratic nomination. However his age is a concern - he would be 79 on inauguration day.

Julian Castro, a former San Antonio mayor, has been widely tipped as a rising star in the Democratic Party for years and served in Barack Obama's Cabinet. The grandson of a Mexican immigrant, Mr Castro has sought to use his family’s personal story to challenge Mr Trump’s border policies.

John Delaney, a congressman from Maryland, was the first to throw his hat into the ring when he made his announcement in September, 2017. The 55-year-old’s pitch is unashamedly moderate. This could prove a weakness given his lack of name recognition and no eye-catching policies to set him apart in a crowded field.

Tulsi Gabbard, an Iraq War veteran who is the first Hindu elected to Congress and the first member born in the US territory of American Samoa, said “the issue of war and peace” would be the main focus of her campaign. The 37-year-old has drawn criticism for meeting with President Bashar Assad and questioning his role in a chemical attack on civilians.

Kirsten Gillibrand, a senator for New York, is an outspoken Trump critic and champion of women’s issues including the #MeToo movement. The 52-year-old has presented herself as a young mother fighting for better healthcare, combating “institutional racism” and taking on entrenched systems of power in Washington.

Kamala Harris, a senator for California, is striking a balance between progressive policies such as medicare for all and more moderate approaches to gun rights and foreign policy. The 54-year-old's supporters believe she has a broad enough appeal to gain traction with a Democratic Party that is increasingly non-white and fuelled by women.

Pete Buttigieg, started out a little known 37-year-old mayor, but has quickly become a top-tier candidate. Mr Buttigieg has held no national political office but has an impressive CV. It includes having served as a counterintelligence officer in Afghanistan, a Harvard degree and a Rhodes scholarship at Oxford. The only millennial and openly gay candidate in the race, he has framed his White House bid around his youth.

Amy Klobuchar, a senator for Minnesota, has positioned herself as the most prominent Midwestern candidate in the field, as her party tries to win back Trump voters in the region. The 58-year-old granddaughter of an iron miner calls herself a pragmatist, advocating gun control and universal health care, while calling for America to support its troops.

The 46-year-old Texan gained a national following with his long-shot election battle against Senator Ted Cruz last year. Mr O'Rourke's message of inclusion and optimism got America’s liberal elite swooning, and many believe he could be the candidate to achieve the near impossible and turn Texas blue in 2020.

Cory Booker, a senator for New Jersey who has styled himself a "street fighter", is a major contender. The 48-year-old is one of only three black US senators and has an impeccable academic CV - political science at Stanford, a Rhodes scholarship to Oxford, going on to study law at Yale.

Bill de Blasio, the mayor of New York city, has plenty of name recognition but this may not count in his favour. Polls suggest most New York voters are against the idea of the 6ft 5in mayor, known as "Big Bird", entering the 2020 race.

Jay Inslee, the governor for Washington state, is running almost exclusively on a climate change platform - the only candidate in the race to do so. The 68-year-old is a vocal critic of Mr Trump and attempted to sue the president after he attempted to implement his Muslim ban.

John Hickenlooper, is a former governor of Colorado, former Denver mayor and pub owner. The 67-year-old's sales pitch is that he is an "extreme moderate" – a pro-business Democrat who is also socially progressive. But his lack of name recognition will hold him back in a crowded field.

Marianne Williamson is a best-selling author and spiritual teacher, but perhaps best known for being presenter Oprah Winfrey's spiritual counsellor. The 66-year-old ran an unsuccessful campaign for the House of Representatives as an independent candidate in 2014. Her presidential campaign calls for "a moral and spiritual awakening in the country".

Andrew Yang, an entrepreneur and businessman, says he wants to introduce a universal basic income of $1,000 per month for all Americans to address economic inequality. The 44-year-old has focused his campaign on "human-centred capitalism". While he struggles to get national name recognition, his donations have reached the threshold to earn him a spot at the first Democratic debate.

Michael Bennet, a senator for Colorado, is perhaps best known for being part of the so-called 'Gang of Eight' bipartisan group which wrote the first draft of a 2013 immigration bill. The 54-year-old announced his bid for the presidency in early May - joining his former boss, John Hickenlooper, in the crowded field.

Seth Moulton, 40, is a congressman from Massachusetts. A Harvard graduate and former US marine, he has defined himself as a progressive, supporting legalisation of cannabis, the green new deal and further gun control. However he has failed to secure a spot in the first round of debates, which is crucial for national recognition.

Eric Swalwell a congressman from California, has taken a particularly tough line on guns in his campaign, calling for a ban on assault weapons. Firmly tilting to the left of the party, the 38-year-old has endorsed the Green New Deal and backs Medicare for All, which would eliminate most private health insurance.

Tim Ryan was elected to Congress at just 29 years old to represent Ohio. He has called for his party to reclaim working class voters in the Midwest who switched turned to Donald Trump in 2016. The 45-year-old is a middle of the road Democrat, calling for tough action on climate change and a new public health insurance system.

Steve Bullock is the governor of Montana, a state that Donald Trump won easily in 2016, and is seen as a pragmatist who can work with Republicans to achieve his goals. The 53-year-old has focused on reforming campaign finances, but his late entry to the race poses a challenge and he has failed to qualify for the first round of debates.

Wayne Messam, the mayor of Miramar, is the only candidate from Florida, the country's largest swing state. The 45-year-old's advisers say one of his main policy proposals will be forgiving the $1.5 trillion in student debt currently owed by 44 million Americans. Mr Messam says he's not willing to concede defeat, despite not making the cut for the first debates.

Joe Sestak, a retired three-star Navy admiral, waited until late June to throw his name into the field. The 67-year-old is running on his lengthy naval career, which has spanned from the Vietnam and Cold War eras, to Afghanistan and Iraq and the emergence of China. His late entry disqualifies him from the first debates.