Bernie Sanders has ended his campaign for the 2020 Democratic presidential nomination.
The 78-year-old's departure from the race leaves a clear run for rival Joe Biden to take on Donald Trump in November.
The Vermont senator's hopes at the candidacy were dashed when South Carolina and several other battleground primaries were won by Mr Biden.
Analysts put Mr Sanders' decline down to the coronavirus crisis forcing the cancellation of political rallies, which is where he thrived.
Mr Sanders told supporters on a video call 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."
He resisted calls to stand down early after Super Tuesday and used the backdrop of the escalating Covid-19 infection rate in the US to thrust his progressive agenda.
But his campaign suffered as an increasing number of Democrats backed the moderate candidate Mr Biden.
His move to withdraw has been seen by many as a repeat of the 2016 presidential race, when he lost to moderate Hillary Clinton.