Saying "we need you in the White House," Sen. Bernie Sanders endorsed Joe Biden for president on Monday, less than a week after suspending his own campaign for the Democratic Party nomination.

The Vermont senator made the announcement during a livestreamed virtual event with Biden, the former vice president who is now his party's presumptive presidential nominee.

SANDERS SUSPENDS 2020 CAMPAIGN

"We are in a terrible moment, an unprecedented moment and I know we share the understand that we have to go forward, right now and out of this, in an unprecedented way to address the terrible pain that so many of our fellow Americans are feeling," Sanders said.

"So today I am asking all Americans, I’m asking every Democrat and 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, to make certain that we defeat somebody who I believe, and I’m speaking just for myself now, is the most dangerous president in the modern history of this country," he said.

The announcement settles speculation on whether and when Sanders would formally back his former primary rival. He notably did not endorse when he suspended his campaign last week, stoking speculation about a lingering ideological divide -- one which still may persist between Sanders supporters and the Biden camp.

In a curious moment during last week's announcement, Sanders even highlighted that he would keep his name on the upcoming primary ballots and stressed the importance of continuing to win delegates for his own campaign so he'd be able to exert "influence" on the party platform.

But Biden was visibly reaching out to Sanders and his base, adjusting his own campaign platform in a bid to make it more appealing to progressive voters, many of whom had backed Sanders.

Biden said in a statement last week that Sanders and his supporters "changed the dialogue."

In Monday's announcement, Sanders pointed to the coronavirus crisis facing the nation and emphasized to Biden that "we don’t have a choice. We have to come together."

The independent who was making his second straight White House run announced that the two campaigns were teaming up for six working groups to tackle the key issues of the economy, education, climate change, criminal justice reform, immigration reform, and health care.

"I have been very pleased that your staff and my staff have been working together over the last several weeks to coming up with a number of task forces that will look at some of the most important issues facing this country," Sanders said.

The senator acknowledged that "it’s no great secret out there, Joe, that you and I have our differences and we’re not going to paper them over. That’s real. But I hope these task forces will come together utilizing the best minds – people in your campaign and in my campaign – to work out real solutions to these very, very, important problems. I look forward to working with you and bringing some great people into those task forces."

A gracious Biden thanked his rival, saying, "Bernie, I want to thank you for that. It’s a big deal. Your endorsement means a great deal to me. I think people are surprised that we are apart on some issues but we’re awfully close on a bunch of others."

And he joked that "you just made me" the nominee.

The former vice president spotlighted that "I’m going to need you – not just to win the campaign – but to govern."

The day after Sanders ended his White House bid, Biden showcased new proposals to lower the Medicare eligibility to age 60 and forgive student loan debt for low-income and middle-class families.

In reaching out to the left, the former vice president credited the populist firebrand and his legions of progressive and younger supporters for his embrace of the proposals.

The move was a significant step toward Sanders’ push for a government-run "Medicare-for-all" single-payer health care system, which was the senator’s signature domestic proposal in his 2020 presidential campaign. But it doesn’t go as far as Sanders’s plan, which calls for phasing in all Americans over a four-year period and phasing out private health insurance plans.

Biden, Sanders, and the Democratic Party as a whole are all trying to avoid a repeat of the bitterness of the 2016 campaign, when many Sanders supporters refused to support eventual nominee Hillary Clinton in her general election showdown with Donald Trump. The deep divisions in the party were a contributing factor in Trump’s upset victory over Clinton in the presidential election.

For Biden – who needs the support of progressives in order to unify the party as he challenges President Trump – a delicate dance is ahead. The former vice president clearly needs to embrace more of Sanders’ progressive agenda if he wants to seal the deal with that part of the base.

But going too far left may leave Biden vulnerable to attacks from Trump that he’s pushing a socialist agenda. Trump and his allies have hammered the message since the beginning of the cycle that the Democratic Party has drifted far to the left of most Americans. They are eager to paint Biden with that brush.

Minutes after Sanders endorsed Biden, Trump campaign manager Brad Parscale argued that "this is further proof that even though Bernie Sanders won't be on the ballot in November, his issues will be."

Ahead of the Sanders endorsement, the Biden campaign spotlighted their efforts to reach out to progressive leaders and organizations in the past several weeks.

“We are continuously considering and evaluating additional policies that would build upon Vice President Biden's progressive agenda,” Biden spokesman Matt Hill told Fox News.

“The most important piece of engaging progressive leaders and groups is to ensure we're expanding and broadening our coalition to beat Donald Trump in November, and we are working with these leaders and groups to align on our efforts to do that. Defeating Trump is the universal commitment that we all share," he emphasized.

A former Sanders aide told Fox News after the announcement that the senator "always said he was going to fully support the nominee and do everything he could to help them get Trump out of office, so this is just making good on his word which Bernie Sanders always does."

Sen. Elizabeth Warren, D-Mass., who is closer ideologically with Sanders, still has not endorsed anybody since suspending her presidential campaign, and has not responded to requests for comment on an update.

Fox News' Madeleine Rivera, Allie Raffa, Andrew Craft, and Tara Prindiville contributed to this report.