Sen. Bernie Sanders endorsed former Vice President Joe Biden for president on Monday during a livestreamed conversation between the two men, telling Biden "we need you in the White House."

"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," Sanders said.

The Vermont senator exited the Democratic primary on Wednesday, effectively making Biden the apparent nominee to take on President Donald Trump in November.

The endorsement was expected, though the timing was a surprise, and could give Biden a boost as he seeks to rally the party's young liberals who backed Sanders in 2016 and again in 2020.

Biden called the endorsement a "big deal," including to him personally.

"If I am the nominee, which it looks like now you just made me, I am going to need you, not just to win the campaign, but to govern," Biden said. The former rivals appeared via split screen in an online conversation that lasted about half an hour.

Sanders' endorsement of Biden comes far earlier in the cycle than the Vermont lawmaker's 2016 endorsement of Hillary Clinton, who bested Sanders for the nomination that year.

Sanders endorsed Clinton in July 2016, more than a month after she had secured enough delegates to clinch the nomination. Biden has yet to secure a majority of the delegates up for grabs this cycle. The perception that Sanders did not work hard enough to convince his supporters to vote for Clinton has left anger among some Democrats.

Relations between Biden and Sanders appear to be considerably warmer, with the two men having apparently been in talks in recent weeks on policy.

Sanders said that his staff had been working with Biden's team to come up with a number of "task forces" to address the pressing issues of the day, listing the economy, education, climate, criminal justice, immigration reform and health care. A Sanders aide said the composition of the task forces was still being worked out.

"It's no great secret Joe that you and I have our differences, and we are not going to paper them over. That's real," Sanders said. "But I hope that these task forces will come together, utilizing the best minds and people in your campaign and in my campaign, to work out real solutions to these very, very important problems."

Biden, for his part, said that he looked forward to welcoming Sanders's supporters into his campaign and said that he and Sanders were friends.

Their livestreamed discussion was for the most part somber, focused on the immense economic toll caused by coronavirus — but was lighthearted at times, with Sanders at one point joking that the two should play chess.

"You don't get enough credit, Bernie, for being the voice that forces us to take a hard look in the mirror and ask ourselves if we've done enough," Biden said admiringly of Sanders at another point. "And we haven't."