As many as 20 opposition Democrats appear to believe they can beat Donald Trump at the 2020 US presidential election. SBS News looks at some of the most likely Democrats to go the distance, according to early polls.
Former United States Vice President Joe Biden has formally entered the race to be the country's next president.
The 76-year-old, who has already run twice for the presidency, enters a very crowded race for the 2020 Democratic nomination.
As many as 20 opposition United States Democrats are looking to take current US President Donald Trump's job next year. The pool is among the largest and most diverse ever.
But before any of them can challenge Mr Trump for the presidency, they must win enough internal support from fellow Democrats and be named the party's official presidential nominee.
So, who are the early front runners?
Barack Obama's vice-president Joe Biden is the most experienced of the bunch.
Mr Biden said he was spurred to run after Mr Trump's comments in the wake of a deadly white supremacist rally and counter-rally in Charlottesville, Virginia in 2017. Mr Trump said there were "very fine people on both sides".
"With those words, the President of the United States assigned a moral equivalence between those spreading hate and those with courage to stand against it. And at that moment, I knew the threat to this nation was unlike I had ever seen in my lifetime,” Mr Biden said in a video posted on Twitter.
Mr Biden has unsuccessfully run for president twice before. He has long been popular in centrist Democratic circles, but his image has taken a hit in recent times with high profile allegations of touching women inappropriately.
Mr Biden has also faced criticism since the #MeToo era began for a series of incidents while serving as chair of the senate judiciary committee in the early 1990s. He allowed an all-male and all-white panel to aggressively question Anita Hill, an employee of then-supreme court justice nominee Clarence Thomas, who had accused him of sexual harassment.
Mr Biden's experience could actually hamper his chances of beating Mr Trump if he was to win the Democratic nomination, according to some analysts.
“He has a very long record of service for his opponents to mine and use against him – and that's already playing out," Dr Emma Shortis, from RMIT University’s Social and Global Study Centre, told SBS News.
"We're looking at four or five decades of service that people can comb through, as they rightly should."
Mr Biden is seen as a frontrunner to secure the Democratic nomination, alongside Vermont Senator Bernie Sanders.
Senator Sanders made an unsuccessful run for the presidency in 2016 - but his pledges to fight for universal health care, and fight against climate change and wage inequality, galvanised a younger generation of voters.
The groundswell of support Senator Sanders experienced in 2016 will likely stand him in good stead this time around, as will his ability to raise funds.
However, the US might not be ready for a Sanders presidency, Dr Shortis said.
“I think Sanders is probably still a bit too radical,” she said.
"He has proved that he has significant fundraising power, but I'd be more inclined to think the Democrats would settle on more of a compromise candidate – maybe somewhere between Biden and Sanders.”
California Senator Kamala Harris is a 54-year-old hard-nosed attorney.
The daughter of an Indian immigrant medical researcher mother and a Jamaican economist father, Senator Harris began her career as a district attorney in San Francisco before serving as California's attorney general.
Analysts say she fits in with the "new wave" of younger, more diverse and progressive Democrats.
Senator Harris, who would be the US' first female and black female president, announced her candidacy on a day honouring slain civil rights icon Martin Luther King Jr.
It is expected Senator Harris will be tested in the coming months, particularly given the gender and racial division in the present day US.
“She is a woman of colour, and in the Trump era, I think that means Harris has a significant hill to climb, even if I think she is capable of overcoming that to a degree,” Dr Shortis said.
Former congressman Beto O'Rourke was unsuccessful in unseating Texas Senator Ted Cruz in last year's mid-term elections but won plenty of admirers in the process.
He was a heavy underdog when challenging Senator Cruz, a Republican in a mostly conservative state, and only lost the race by less than three percentage points - the closest Senate contest in the state in four decades.
The 46-year-old centrist's energy and charisma have helped set fundraising records and draw support from celebrities.
Few of Mr O'Rourke's competitors can match his likability, Dr Shortis said.
He could also help the Democrats win back support in some of the states which voted for Mr Trump in 2016, she added.
"Because he came so close to clinching an election victory in somewhere likes Texas, which is traditionally a Republican fortress, that lends him a lot of credibility.
“I think he's also reflective of a broader debate that's going on within the Democratic Party about what they have to do to win back the fabled white, working-class voters that lost those crucial rough-belt states in the electoral college."
Other prominent candidates include 69-year-old Massachusetts Senator Elizabeth Warren, a progressive Democrat who built her reputation by holding banks accountable for missteps, and New Jersey Senator Cory Booker, a community activist who has been compared to Barack Obama.
Pete Buttigieg - the 37-year-old mayor of South Bend, Indiana - would be the first openly-gay prominent presidential nominee of either major party.
The Democrat's pick for its nomination, whoever it is, will give the clearest signal yet of its post-Trump identity, Dr Shortis said.
“I would resist making predictions or saying 'these are the frontrunners' because people will also start to drop out as they realise it's not necessarily going to go well for them,” she said.
“But who the Democrats choose as the nominee will absolutely reflect the choice that they make about the strategy and politics they think is going to defeat Trump and win them more support beyond that.”