Bernie Sanders has endorsed Joe Biden for president of the United States, calling for unity in the Democratic Party less than a week after ending his own campaign.

“I am asking all Americans, I’m asking every Democrat, I’m asking every independent, I’m asking a lot of Republicans to come together in this campaign to support your candidacy, which I endorse,” he said, appearing alongside the former vice president in a livestream broadcast.

In the joint broadcast, during which the two former rivals discussed shared policy goals, the senator from Vermont described Donald Trump as “the most dangerous president in the modern history of this country”.

“We have to make Trump a one-term president and we need you in the White House,” Mr Sanders added.

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Mr Biden said he would work with Mr Sanders to form a progressive administration that would reach out to his supporters.

“I believe there is a great opportunity to work together,” Mr Biden said. “I appreciate your friendship and I promise I will not let you down.”

Mr Sanders ended his campaign last week after Mr Biden put together an insurmountable lead in the Democratic primary. An early frontrunner of the 2020 campaign, Mr Sanders energised young and progressive voters by championing policies like universal healthcare and taxing the wealthy.

The race was turned upside down on Super Tuesday, when the former vice president racked up big wins in delegate-rich states like Texas and Virginia.

Mr Biden will now face the challenge of winning over diehard Sanders supporters who view him as the candidate of the Democratic Party establishment.

In the broadcast on Monday, Mr Biden said he would establish six policy working groups with Mr Sanders to bridge the gap between their campaigns, on issues such as the economy, climate change, criminal justice and education.