Sen. Bernie Sanders (I-Vt.) endorsed former Vice President Joe Biden s presidential campaign on Monday, appearing on a livestream with his former rival for the Democratic nomination to stress the importance of defeating President Donald Trump.

Im asking every Democrat, Im asking every independent, Im asking a lot of Republicans, to come together in this campaign to support your candidacy, which I endorse, Sanders, who dropped out of the 2020 presidential race last week, told Biden.

Democrats hope Sanders speedy endorsement of Biden will help heal the party following a primary that revealed sharp ideological disagreements among the partys core supporters and left many of Sanders young supporters disillusioned. While early public opinion surveys show Biden with a lead over Trump, his margin among young voters is smaller than the advantages Hillary Clinton or Barack Obama had during their presidential campaigns.

Sanders acknowledged there were significant policy differences between his vision of democratic socialism and Bidens center-left views, but he said the campaigns would create joint task forces to develop policy positions on key issues, including on the economy, education, criminal justice, immigration and climate change.

Your endorsement means a great deal to me, Biden told the senator. Im going to need you, not just to campaign, but to govern.

Sanders has pledged to support the Democratic nominee since launching his presidential campaign in early 2019. Since suspending his own run for the White House, he has said his advisers would continue working with Bidens team to present a united front. Sanders joins a long list of former Democratic presidential candidates who have thrown their support behind Biden. One notable exception is Sen. Elizabeth Warren (D-Mass.)

Biden has signaled an openness to shifting his agenda leftward. He said he supported canceling student debt for a large portion of Americans who make less than $125,000 a year and has also adopted a Warren proposal to repeal a bankruptcy law he once championed.

Bidens opening bid to progressives has been met with mixed reviews. Some of Sanders top surrogates have balked at the proposals. Rep. Alexandria Ocasio-Cortez (D-N.Y.) told The New York Times she felt Biden wasnt making a serious effort to reach out to the left wing of the party.

The whole process of coming together should be uncomfortable for everyone involved thats how you know its working, she said. And if Biden is only doing things hes comfortable with, then its not enough.

She added that Bidens so-called progressive concession on health care was less ambitious than what Clinton supported in 2016. Sanders said something similar himself when Biden endorsed making public colleges and universities tuition-free for families with incomes less than $125,000 in mid-March.

Still, many progressive groups see plenty of opportunity to influence Biden. Eight progressive groups, all of which have mostly young followings, pushed Biden to adopt a suite of left-wing policies in a letter last week , promising to spend $100 million to help turn out young voters. Among them was Justice Democrats , the political action group that famously backed Ocasio-Cortezs upset victory over an incumbent in 2018.

The announcement of joint Sanders-Biden policy task forces is a good step forward and is aligned with key parts of the #EarnOurVote letter sent out by progressive millennial and youth organizations, said Waleed Shahid, a spokesperson with Justice Democrats, noting that the group is still waiting for details about the task forces.

On Monday, Biden and Sanders seemed to take turns echoing each others talking points. Sanders emphasized the importance of beating Trump above all else, calling the incumbent the most dangerous president in the modern history of this country a major theme of Bidens campaign.

A president who apparently has never read the Constitution of the United States, who believes hes above the law, a president who lies all of the time, who has at least shown me that he is a racist and a sexist and a homophobe and a xenophobe and a religious bigot, Sanders said. For all those reasons and more, weve got to make him a one-term president.

At the same time, Biden emphasized the importance of an agenda focused on the working class, arguing the Trump administration was working to ensure the response to the coronavirus pandemic and recession was tilted toward the wealthy and well-connected.

The idea that we are still arguing whether health care is a right is bizarre, Biden told Sanders during their livestreamed conversation. (Biden has yet to support a universal health care program.) The former vice president also reiterated his support for organized labor.

You and I have shared the profound conviction this country wasnt built by Wall Street, Biden said.

Trump and his campaign have been open about their desire for the Democratic Party to remain divided, hoping to either lure Sanders supporters over to the GOP or to discourage them from voting altogether. The campaigns statement on Sanders endorsement tried to simultaneously scare moderates by linking Biden to Sanders left-wing agenda and discourage young people by arguing Biden was part of the Democratic establishment.

This is further proof that even though Bernie Sanders wont be on the ballot in November, his issues will be. Biden had to adopt most of Bernies agenda to be successful in the Democrat primaries, Trump campaign manager Brad Parscale said. And while Biden is the Democrat establishments candidate, President Trump remains the disruptor candidate who has brought change to Washington. President Trumps supporters will run through a brick wall to vote for him. Nobody is running through a brick wall for Joe Biden .

Sanders endorsement of Biden comes much earlier in the election year than his decision to back Clinton four years ago. After waiting until June to drop out of the race and then withholding his endorsement from Clinton more than a month in 2016, Sanders waited less than a week to endorse Biden in 2020. Aides to both men have emphasized how much each respects the other in recent weeks.

I promise you I will not let you down, Biden told Sanders on the call in his closing remarks.