In 2016, Bernie Sanders endorsed Hillary Clinton on July 12, two weeks before the start of the Democratic convention. This year, Sanders endorsed Joe Biden on April 13, offering much more time for the party to achieve the unity it needs to prevail in November.

As befits the moment, they did it over a joint livestream.

“Today, 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,” said Sanders.

“We’ve got to make Trump a one-term president, and we need you in the White House,” Sanders continued. “I will do all that I can to see that that happens, Joe.”

Some of Sanders’s more impassioned supporters will not accept Sanders’s argument. Indeed, one prominent backer immediately announced she will not endorse Biden, because he is not for Medicare-for-all or for the robust social democratic proposals on taxing wealth and free college that Sanders backs.

But this move’s importance has little to do with such supporters. Instead, what will matter is the impact it has on the many millions of people who voted for Sanders but merely need more reassurance about Biden before they can back him.

And let’s be clear: Biden still does have plenty of work ahead if he is going to win over those people.

The crucial thing to note here is that both Biden and Sanders appear to understand this, and want to do something about it.

Their latest joint appearance demonstrates this. The two men also announced that they’ll be forming six task forces to devise policy ideas, on the topics of the economy, education, health care, criminal justice, immigration and climate change.

This is potentially significant, because it shows they both are eager to communicate that Sanders will continue to have an influence on Biden. True, there’s a long history of such working groups having their ideas ignored. But at the very least they will be a vehicle for Sanders and his representatives to continue communicating their ideas directly to Biden’s people — and will create a way for Sanders supporters to judge whether those ideas really are influencing Biden.

This evolving structure is something that Sanders appears to want to see. As we reported, the Sanders team has come to believe that Biden and his advisers genuinely grasp the need to undertake meaningful bridge-building to the Sanders wing of the party.

What’s more, Sanders advisers expect the Biden campaign to roll out proposals designed to win them over in stages. And they want to give Biden space to prove their good intentions in this regard.

Sanders himself signaled the contours of what this will look like in an interview last week with Chris Hayes.

Biden had just rolled out two policy proposals. One expanded the Medicare eligibility age to 60, which, when taken with his public option, would be a real expansion of government health care and a change in Biden’s underlying posture toward social programs, though many understandably criticized it for not going far enough. The other would forgive student debt for many with an income of $125,000 and under.

Sanders told Hayes that, while he would have gone considerably further, these proposals constituted real movement in the right direction.

“What you have begun to see, and what you will continue to see, is the vice president is listening to many of the concerns that low income people and working people and young people have, and beginning to move in their direction,” Sanders said.

What’s clear is that Sanders and Biden seem determined to create a framework in which Biden genuinely can and does evolve toward Sanders’s vision. Sanders seems to be saying that, even if by his and his supporters’ lights this evolution will not be as ambitious as what they’d hoped for in a nominee, Biden is inviting them to have real influence over him, in the old Franklin D. Roosevelt “make me do it” vein.

The evolving structure here looks something like what writer David Atkins outlined, in which Sanders supporters accept that they actually are having success pulling the Democratic Party to the left, and that this is both meaningful and opens up possibilities for future organizing and politicking:

The reality is that leftist policy has never been more ascendant in the Democratic Party since at least the 1960s if not the 1930s. The Biden 2020 campaign platform is well to the left of the Clinton 2016 platform, which was itself well to the left of the Obama 2008 platform. … Most of those advances are due to the hard work of leftists whose tireless advocacy has successfully won the force of moral argument and persuaded mainstream Democratic base voters and independents.

Atkins advised disappointed Sanders supporters to embrace “the Democratic Party and its voters as a positive force for change,” and work toward a strategy of “leftist policy maximization” in that context, rather than “seeing the party and its voters as an obstacle” to deeper class-politics-driven transformation.

This appears to be the understanding that Sanders is consciously inviting his supporters to adopt as well.

One thing to watch for now, as Democratic strategist Simon Rosenberg told us, is whether this unifying moment expands Biden’s support. While Biden’s national lead over Trump is probably not as meaningful as it seems due to Trump’s clear structural advantages, a small bounce could mean a lot in this environment.

“If Biden picks up even two or three points, it will make it more likely the Senate flips this November, too,” Rosenberg said.

For his part, Biden seems to share in Sanders’s understanding of the situation. Biden got plenty of justifiable criticism over his smallness of vision and relentless focus on restoration first, but he now seems to appreciate that this won’t cut it.

“We just can’t think about building back to the way things were before,” Biden said on the livestream. “It’s not enough. We need to build to a better future.”

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