Once a pool of more than 25 has now been reduced to just one.

Former Vice President Joe Biden is the last candidate in the 2020 Democratic presidential race.

His now-likely nomination comes after Senator Bernie Sanders, once a Democratic frontrunner, ended his bid in April, saying he the “path toward victory was virtually impossible”.

The race has been upended by the coronavirus pandemic, which forced campaigns online, delayed primary elections and force the Democratic National Committee to postpone its nominating convention.

Here’s a brief look at who Biden is, and the list of candidates that dropped out ahead of November’s election.

Joe Biden, 77

Joe Biden served as vice president under former President Barack Obama from 2009 to 2017 after nearly four decades serving as a senator from Delaware.

Biden is the most experienced politician in the race and among the oldest at 77. This will be his third presidential run. His first White House bid in 1987 ended after a plagiarism scandal.

In a video announcement of his candidacy posted on Twitter on April 25, Biden focused on the 2017 deadly clash between white supremacists and counterprotesters in Charlottesville, Virginia. Biden noted US President Donald Trump‘s comments that there were some “very fine people” on both sides of the violent encounter, which left one woman dead.

“We are in the battle for the soul of this nation,” Biden said. “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 watch that happen.”

Last year, Biden struggled to respond to comments from Lucy Flores, a 2014 lieutenant governor nominee in Nevada, who said he made her uncomfortable by touching her shoulders and kissing the back of her head before a campaign event. Several other women have made similar claims.

In a video, Biden pledged to be “more mindful” of respecting “personal space”, but Flores told Fox News this week that the former senator’s jokes on the matter have been “so incredibly disrespectful”.

The incident is just a glimpse of the harsh vetting from both Democrats and Republicans expected for Biden, who has run for president twice before but never from such a strong political starting position.

Former Vice President Joe Biden speaks at the Biden Courage Awards last year in New York. [Frank Franklin II/AP Photo]

Last year, he was also repeatedly forced to explain his 1991 decision, as Senate Judiciary Committee chairman to allow Anita Hill to face questions about her allegations of sexual harassment against Clarence Thomas, then a nominee for the Supreme Court.

Biden has since apologised for his role in the hearing. But in the #MeToo era, it is another example of why critics believe he may struggle to catch on with the Democratic primary voters of 2020.

Biden was also becoming a prominent figure in the House of Representatives impeachment inquiry of Trump. That probe is centred on a July 25 phone call in which Trump pressed Ukrainian President Volodymyr Zelenskyy to investigate Biden and his businessman son, Hunter.

Democrats have accused Trump of pressuring Ukraine to find incriminating information on Biden after withholding nearly $400m in US security aid to Ukraine. There has been no evidence of wrongdoing by the Bidens. In December, the Democratic-controlled House of Representatives impeached Trump for abuse of power and obstruction of Congress. The president was acquitted in February.

Biden made all debate stages during the campaign season. He struggled to maintain his early momentum in the first three contests of the primary season but got a boost for his campaign in the South Carolina primary.

Who has dropped out?

Michael Bloomberg

Michael Bloomberg served as New York City mayor from 2002 to 2013. The 78-year-old billionaire who entered the race in November decided to forego the four states with the earliest primaries and caucuses, focusing instead on states like California that vote on Super Tuesday.

A disastrous showing on Super Tuesday, in which he managed a win only in the US territory of American Samoa, made it clear he had no path forward, however, so he dropped out on March 4 and endorsed Biden.

Michael Bennet

Michael Bennet has served as a US senator from Colorado since 2009. Bennet, a former head of the Denver school district, carved out a profile as a wonky, policy-oriented senator.

But his profile did not do him any favours, never catching on in the polls or in his fundraising.

Bennet announced the end of his campaign on February 11, the night of the New Hampshire election.

Cory Booker

Cory Booker has served as a US senator from New Jersey – the first African American in the state’s history to hold the office since 2013. He was the mayor of Newark from 2006 to 2013.

After struggling in the polls and fundraising, Booker dropped out of the race in January.

“It’s with a full heart that I share this news – I’m suspending my campaign for president,” he tweeted when announcing he was ending his bid.

“To my team, supporters, and everyone who gave me a shot – thank you. I am so proud of what we built, and I feel nothing but faith in what we can accomplish together,” he added.

Booker had qualified for five debates but failed to meet the requirements for the sixth event.

Steven Bullock

Montana Governor Steve Bullock quit his bid for the Democratic nomination in early December.

“Today, I am suspending my campaign to become the Democratic Party’s nominee for president,” Bullock, 53, said in a statement on December 2. “While there were many obstacles we could not have anticipated when entering this race, it has become clear that, in this moment, I won’t be able to break through to the top tier of this still-crowded field of candidates.”

Bullock, 53, will return to Montana to finish his second term as governor. He will not run for the US Senate, despite encouragement from party leaders to do so and help Democrats wrest control of Congress’s upper house from Republicans.

Bullock was re-elected in conservative Montana in 2016, making him the only Democratic presidential contender who had won a statewide election in a state Trump carried in 2016.

Bullock failed to make the presidential debate stage in June but did so in July. Due to the stricter guidelines for the events in September, October and November, he did not qualify.

Pete Buttigieg

Pete Buttigieg, the former South Bend, Indiana, mayor who was a rising star in the Democratic Party, dropped out of the race on March 1, just before Super Tuesday.

“I will no longer seek to be the 2020 Democratic nominee for president, but I will do everything in my power to ensure that have a new Democratic president come January,” he told supporters in South Bend.

“We need leadership to heal a divided nation, not drive us further apart,” he said, apparently warning against giving Sanders the nomination.

Buttigieg made history as the first openly gay Democratic candidate to run for president. He won the delegate count in the chaotic Iowa caucuses.

Buttigieg qualified for all debates held before he dropped out.

Julian Castro

Julian Castro was elected mayor of San Antonio, Texas in 2009 and served until 2014.

He served as the 16th US secretary of Housing and Urban Development (HUD) under US President Barack Obama from 2014 until 2017.

He ended his presidential bid in January, saying in a video: “I’ve determined that it simply isn’t our time.”

He said he was not done fighting. “I’ll keep working towards a nation where everyone counts, a nation where everyone can get a good job, good health care and a decent place to live.”

Castro made the debate stage for the first four events, but failed to qualify for the fifth and sixth debates.

Bill de Blasio

The New York City mayor emerged as a progressive standard-bearer in 2013, when he won the first of two four-year terms at the helm of the country’s biggest city on a platform of addressing income inequality. But he struggled amid middling approval ratings and some political setbacks to build a national profile.

After making the first two 2020 Democratic debates, but failing to qualify for the September event, the New York City mayor dropped out of the race in mid-September.

“I feel like I’ve contributed all that I can to this primary election,” de Blasio told MSNBC when announcing he was withdrawing from the race. “It’s clearly not my time.”

John Delaney

John Delaney served as a US congressman for Maryland’s sixth district from 2013 to 2019.

He was the first Democrat to formally declare a run for the party’s 2020 presidential nomination, but at the end of January, he said he was dropping out of the race.

Delaney, who had already been campaigning for more than a year, announced the end of his presidential run in an interview on CNN.

He failed to qualify for the first debate but was able to do so for the second. He could not, however, meet the guidelines for the rest of the debates.

Tulsi Gabbard, 38

Tulsi Gabbard has served as a US congresswoman from Hawaii’s second district since 2013.

She dropped out on March 19 and endorsed Biden.

Kirsten Gillibrand

Kirsten Gillibrand has served as a US senator from New York since 2009.

After failing to qualify for the third Democratic presidential debate, Gillibrand, who campaigned on a platform centred on women’s rights, dropped out of the race.

In announcing her decision on August 28, Gillibrand told US media she had not decided which candidate to endorse.

“I think that women have a unique ability to bring people together and heal this country,” Gillibrand told the New York Times newspaper.

“I think a woman nominee would be inspiring and exciting,” she added.

Mike Gravel

Mike Gravel, the 89-year-old former senator, made a little-known run for the Democratic nomination in 2008 and took another stab at it early in the Democratic race.

His goal was to make the debate stage, but when that did not happen, he officially ended his campaign in August and endorsed Sanders.

Kamala Harris

Kamala Harris has served as a US senator from California since 2017. In early December, she ended her bid for the nomination, saying her campaign did not have the financial resources to continue.

“I’ve taken stock and looked at this from every angle, and over the last few days have come to one of the hardest decisions of my life,” Harris said in an email to supporters. “My campaign for president simply doesn’t have the financial resources we need to continue.”

Harris had qualified for all five debates that took place before she ended her bid.

John Hickenlooper

John Hickenlooper served as the governor of Colorado from 2011 to 2019.

He announced he was ending his presidential bid on August 15 in a video posted on Twitter.

“While this campaign didn’t have the outcome we were hoping for, every moment has been worthwhile and I’m thankful to everyone who supported this campaign and our entire team,” Hickenlooper tweeted.

Later in August, Hickenlooper announced he would run in the US Senate race against Republican incumbent Cory Gardner in Colorado.

Jay Inslee

Jay Inslee has served as the governor of the state of Washington since 2013.

On August 21, he announced he was dropping out of the race, saying, “it has become clear that I’m not going to be carrying the ball. I am not going to be the president.”

Inslee made fighting climate change the central issue of his campaign. In announcing his withdrawal, Inslee said he hoped other 2020 candidates would use his detailed 10-year climate plan.

Amy Klobuchar

Amy Klobuchar served as a US senator from Minnesota since 2007, becoming her state’s first elected female senator.

Before joining the Senate, she was the Hennepin County lawyer.

While she performed better than expected in some of the early voting contests during the primary season, she ended her campaign on March 2, just before Super Tuesday.

She plans to endorse Biden.

Wayne Messam

Wayne Messam has served as mayor of Miramar, Florida, since 2015.

In mid-November, he tweeted that he was suspending his campaign.

Messam had failed to make a single debate stage during the campaign.

Seth Moulton

Seth Moulton has served as the US representative for Massachusetts’s sixth congressional district since 2015.

On August 23, he announced he was dropping out of the 2020 race, telling US media if one of the more progressive candidates won the nomination it could make it harder for the Democrats to beat Trump.

“I think it’s evident that this is now a three-way race between Biden, Warren and Sanders, and really it’s a debate about how far left the party should go,” Moulton told the New York Times newspaper.

Richard Ojeda

Richard Ojeda was the first official presidential contender to drop out of the race.

In January, the former West Virginia state senator announced he was suspending his campaign, acknowledging he “does not have the ability to compete”.

Beto O’Rourke

Beto O’Rourke served Texas’s 16th congressional district in the House of Representatives from 2013 to 2019.

O’Rourke gained fame last year for his record fundraising and ability to draw crowds before his unexpectedly narrow loss in the US Senate race against Republican incumbent Ted Cruz.

On November 1, O’Rourke announced he was dropping out of the presidential race. The New York Times reported that his campaign was facing financial strain.

“My service to the country will not be as a candidate or a nominee,” O’Rourke said in an online post.

“Though it is difficult to accept, it is clear to me now that this campaign does not have the means to move forward successfully,” he wrote on Medium. “Acknowledging this now is in the best interests of those in the campaign; it is in the best interests of this party as we seek to unify around a nominee, and it is in the best interests of the country.”

Deval Patrick

Former Massachusetts Governor Deval Patrick in November 2019 said he was seeking the Democratic Party’s 2020 presidential nomination despite an already crowded race to bring a divided country – and splintering political party – together.

But he announced the end of his bid on February 12, the day after a poor performance in New Hampshire.

“I believed and still believe we had a strong case to make for being able to deliver better outcomes,” Patrick said in a statement. “But the vote in New Hampshire last night was not enough for us to create the practical wind at the campaign’s back to go on to the next round of voting.”

He did not make it to the debate stage during his run.

Tim Ryan

Tim Ryan has served as a US House representative from Ohio’s 13th district since 2003.

On October 24, he announced that he was ending his bid for the nomination and would instead seek re-election in his House race.

Ryan’s campaign was marked by slow fundraising and low poll numbers.

Bernie Sanders

Bernie Sanders served as a US representative for 16 years before being elected to the Senate in 2006 where he currently represents the state of Vermont.

He dropped out of the race in early April, acknowledging that the Biden was too far ahead for him to have any reasonable hope of catching up.

He insisted that his campaign, while unsuccessful, won an “ideological struggle” and opened Americans’ eyes to the importance of his signature issues such as a higher minimum wage and free higher education.

Sanders seized on the ongoing coronavirus pandemic as evidence that his proposal of Medicare for All is even more critical to the country than it was just a few months ago. He said the crisis has “exposed for all to see how absurd our current employer-based health insurance system is”.

He acknowledged that many of his supporters want him to stay in the race, but said he “cannot in good conscience continue to mount a campaign that cannot win” and congratulated Biden, whom he called “a very decent man” that “I will work with to move our progressive ideas forward”.

Joe Sestak

Former US Representative Joe Sestak joined the race in June.

In announcing his candidacy, Sestak, a retired three-star US Navy admiral, emphasised his 31-year military career, the need to restore US leadership in the world and tackle challenges from climate change to China‘s growing global influence.

But after failing to qualify for any of the debates and impress donors, the 67-year-old dropped out of the race in early December.

In a statement posted on his Twitter page, Sestak offered his thanks to supporters “for the honor of running for president” as “I end our campaign together”.

“Without the privilege of national press, it is unfair to ask others to husband their resolve and to sacrifice resources any longer,” he wrote.

Tom Steyer

Tom Steyer, a billionaire donor and liberal activist, announced on July 9, 2019, he was joining the Democratic presidential field after initially saying he would not run to focus his attention on impeaching Trump and getting fellow Democrats elected to Congress.

He said he was ending his bid, however, on February 29, after poor performances in the first four voting contests.

“Honestly, I can’t see a path where I can win the presidency,” he reportedly told supporters in South Carolina.

He said he would continue putting his money behind the Democratic Party.

“Every Democrat is a million times better than Trump. Trump is a disaster,” Steyer was quoted by US media as saying. “So, of course, I’ll be working on that.”

Eric Swalwell

Eric Swalwell, an Iowa native, has served as a House representative from California’s 15th congressional district since 2013.

He dropped out of the presidential race after the first primary debate in June.

Elizabeth Warren

Elizabeth Warren, who dropped out of the race March 5, has served as a US senator from Massachusetts since 2013.

Warren, known as a progressive, taught law at several universities and was a Harvard professor.

Warren is a leader of the party’s liberals and a fierce Wall Street critic who was instrumental in creating the Consumer Financial Protection Bureau.

Marianne Williamson

Marianne Williamson is an author, entrepreneur and activist.

The self-help guru dropped out of the race in January.

“I stayed in the race to take advantage of every possible effort to share our message. With caucuses and primaries now about to begin, however, we will not be able to garner enough votes in the election to elevate our conversation any more than it is now,” Williamson said in a statement.

Williamson qualified for the first two debates, but failed to do so in September, October, November and December.

Andrew Yang

Andrew Yang filed to run for president in 2017.

But the entrepreneur ended his bid on February 11, the day of the New Hampshire primary, after a poor showing in New England state, as well as in Iowa.

Yang failed to qualify for the January debate but did make the cut for the February event.