Bernie Sanders yesterday ended his insurgent campaign for the Democratic presidential nomination, meaning Joe Biden will be the party's presumptive choice to take on Donald Trump in November.
Mr Sanders (78) vowed to work with his Democratic rival to defeat Mr Trump, but said he would continue to fight for his "progressive" policies.
He told supporters of his movement: "Please stay in this fight with me. The struggle continues."
Despite ending his campaign, Mr Sanders will remain on the ballot in states that have yet to vote in the Democratic nomination process.
He will "continue working to assemble as many delegates as possible" at the party's national convention in the summer, he said.
That will allow him to exert "significant influence" over the party's official policy platform going into the November election, pulling all Democrats to the left.
Mr Sanders said: "The path towards victory is virtually impossible.
"While we are winning the ideological battle, and winning the support of so many young people, and working people, I have concluded that this battle for the Democratic nomination will not be successful.
"I congratulate Joe Biden, a very decent man, who I will work with to move our progressive ideas forward. Please know I do not make this decision lightly. In fact it has been a very difficult and painful decision."
Mr Biden thanked his rival for "putting the interest of the nation - and the need to defeat Donald Trump - above all else".
In a message to Mr Sanders's supporters, Mr Biden added: "I see you, I hear you, and I understand the urgency of what it is we have to get done in this country. I hope you will join us. You are more than welcome. You're needed."
Mr Sanders said he understood the views of his most ardent followers who had wanted him to fight on.
But he added: "As I see the crisis gripping the nation, exacerbated by a president unwilling or unable to provide any kind of credible leadership, and the work that needs to be done to protect people in this now desperate hour, I cannot in good conscience continue to mount a campaign that cannot win."
It was the second failed White House bid for Mr Sanders, after he lost to Hillary Clinton in 2016.
In his speech suspending his campaign, delivered on the internet from his home state of Vermont, Mr Sanders said the pandemic showed how necessary his signature Medicare for All healthcare policy was.
He added: "Over the last five years our movement has won the ideological struggle. Raising the minimum wage, guaranteeing healthcare, transforming the energy system and making higher education available to all.
"Not long ago, people regarded these ideas as radical and fringe. Today, they are mainstream ideas. While the path may be slower, now we will change this nation." (© Daily Telegraph, London)
US President Donald Trump sharply criticised the World Health Organization on Tuesday, accusing it of being too focused on China and issuing bad advice during the new coronavirus outbreak and saying he would put a hold on US funding for the agency.