Bernie Sanders just endorsed Joe Biden for president, a sharp departure from his reluctant approach to supporting Hillary Clinton four years ago.

Sanders joined Biden for a chummy-seeming campaign livestream on Monday, where the two longtime lawmakers played up their friendship, praised one another’s integrity and thanked each other for the campaigns they’d run.

“In this terrible moment in our history and given the enormous challenges we face in the future, we don’t have a choice, we’re going to have to come together,” Sanders said, complimenting Biden as “the kind of guy who’s going to be inclusive” in working with people of all stripes towards improving the lives of Americans.

Sanders’ endorsement comes just five days after he suspended his presidential campaign — and a full three months earlier than he endorsed Clinton after a more competitive and in many ways tenser primary.

Four year ago, Sanders refused to drop out before every primary was conducted and Clinton had made some major policy concessions, waiting to endorse her until July 12. That came a full month after he’d been but mathematically eliminated from winning the nomination in early June.

Many Clinton supporters blame Sanders’ foot-dragging for hurting party unity and helping elect Trump in 2016 — his hesitance let Russia sow discord between Sanders supporters and Clinton throughout the race. And while Sanders has long rejected that he’s to blame for Clinton’s loss, it seems he views the election this year far differently.

The existential threats that face the country, the relationship Sanders had with the presumptive Democratic nominee, and how soundly Sanders was losing the primaries all stand apart from 2016. Both Sanders and Biden argued during the livestream, a second Trump poses too dangerous a threat to democracy to win — and the health and economic threat of the coronavirus pandemic made the election even more crucial.

Sanders and Biden have been personally friendly for years — Biden is one of the few establishment politicians that Sanders has had a warm relationship with going back to before his presidential run. The two showed that warmth on the livestream, with Sanders joking about playing chess with Biden rather than end the conversation. It’s hard to imagine that happening with Clinton, who seemed to share a mutual disdain with Sanders throughout the 2016 race.

“I can’t tell you how much I appreciate all that you have done,” Biden said on the video. “We’ve been friends. we’ve disagreed. but we’ve been friends.”

Biden made it clear he’d endeavor to build unity with the Sanders wing of the party, complimenting him time and again for his vision and the movement he’s built.

“You’ve been way ahead,” Biden said to Sanders as he talked about the threat of student loan debt.

Sanders and Biden said their staffs had been working together for weeks to find areas of common agreement. And they’ll formalize that arrangement wit six working groups to develop common and novel ideas on economy, education, criminal justice, immigration and climate change.

Cover: Vermont Sen. Bernie Sanders joined Joe Biden’s livestream and endorsed him for president.