Bernie Sanders has dropped out of the US presidential race, leaving Joe Biden as the likely Democratic nominee to take on Donald Trump.
The Vermont senator has ended his campaign after disappointing primary results.
Mr Sanders told his supporters via a livestream on Wednesday: “I want to thank the hundreds of thousands of volunteers who knocked on doors, millions of them, in the freezing winters of Iowa and New Hampshire, and in the heat, and in South Carolina, and in states throughout the country.
“I want to thank the two million Americans who have contributed financially to our campaign, and showed the world that we can take on a corrupt campaign and finance system, and run a major presidential campaign without being dependent on the wealthy and the powerful.
“Thank you for your 10 million contributions, averaging $18.50 (£14.93) a donation.”
Mr Sanders continued: “As many of you will recall, Nelson Mandela, one of the great freedom fighters in modern world history famously said, and I quote, ‘it always seems impossible until it is done’.
“And what he meant by that is that the greatest obstacle to real social change has everything to do with the power of a corporate and political establishment to limit our vision of what is possible and what we are entitled to as human beings.”
Mr Sanders, who overcame a heart attack on the campaign trail in October last year, had initially exceeded expectations during the race for the Democratic nomination.
But he found himself unable to convert unwavering support from progressives into a viable path to the nomination.
There were also “electability” fears among some, fuelled by questions about whether his democratic socialist ideology would be palatable to general election voters.
The 78-year-old senator began his latest White House bid facing questions about whether he could win back the supporters who chose him four years ago.
Despite winning 22 states in 2016, there were no guarantees he would be a major presidential contender this time around.
However, Mr Sanders used strong polling and solid fundraising to more than quiet early doubters.
He amassed the most votes in Iowa and New Hampshire, which opened primary voting, and cruised to an easy victory in Nevada – seemingly leaving him well positioned to sprint to the Democratic nomination.
But a crucial endorsement of Mr Biden by influential South Carolina Representative Jim Clyburn, and a subsequent, larger-than-expected victory in South Carolina, propelled the former vice president into Super Tuesday, when he won 10 of 14 states.
Mr Sanders’ top former Democratic rivals then lined up and announced their endorsement of Mr Biden.
The former vice president’s campaign had appeared on the brink of collapse after New Hampshire, but found new life as the rest of the party’s more moderate establishment coalesced around him as an alternative to Mr Sanders.
Things only got worse the following week when Mr Sanders lost Michigan, where he had campaigned hard and upset Mrs Clinton in 2016.
He was also beaten in Missouri, Mississippi and Idaho the same night and the results were so decisive that Mr Sanders headed to Vermont without speaking to the media.
The coronavirus outbreak essentially froze the campaign, preventing Mr Sanders from holding the large rallies that had become his trademark and shifting the primary calendar.