CHICAGO — Later today, about 3,000 supporters of Bernie Sanders’s presidential campaign are expected to gather at the McCormick Center to discuss their next moves.

The senator offered his own ideas in a Thursday night simulcast, and the People’s Summit, organized by some of his hardiest organizers, will teem with second opinions.

"You'll have first time organizers who just got off the campaign and say: I want instruction, I want to know the next steps," said Winnie Wong, an Occupy Wall Street veteran and co-founder of the grass-roots group People for Bernie, one of the summit's co-sponsors. "There are going to be more experienced organizers who want to learn how to scale what they did."

The first plans for a post-primary summit were hatched in September 2015, when hopes for Sanders's presidential bid were still relatively modest. National Nurses United, the first union to endorse the campaign, saw the summit as a way to gather Sanders supporters and other elements of the left after what looked likely to be an easy Hillary Clinton victory.

"Back then we just assumed we’d end up with a nominee who’d have to be pushed significantly to the left," said Roseann DeMoro, NNU's executive director. "One of the lessons from Obama years is there was a movement growing, and after it elected a president, the movement went away. Wall Street had free rein, and we didn’t push back. People assumed Obama would do their bidding – which is just crazy, when you look back."

The epic length of the primaries has changed the tone of the summit. While NNU is not among the Sanders endorsers calling on him to officially end his campaign, the focus of the conference is not on winning him the nomination.

One panel will focus on how Sanders supporters can "build power and strategies to take over school boards, city councils, states and Congress," echoing what Sanders asked of his backers on Thursday. A panel on "democratic socialism in a new time" will feature Kshama Sawant, a socialist member of Seattle's city council, and Debbie Medina, a socialist now running as a Democratic candidate for state senate in New York.

After those panels, organizers are planning to organize 300 separate breakout sessions, of 10 people each. The event's scale has grown in the past week — with one exception. Cornel West and Rep. Keith Ellison (D-Minn.), Sanders endorsers who were initially slated to give speeches, had to cancel to attend the second meeting of the Democratic Party's platform drafting committee.

That was a token of Sanders's success, and an example of the balancing act that Sanders's supporters are still learning. There's little talk of ditching the Democratic Party: Jill Stein, who is expected to be the Green Party's nominee for president, was not invited to the conference. There is a debate over whether Sanders should encourage his supporters to back Clinton, or whether an "anti-Trump" movement would be a distraction. And on Thursday night, after organizers watched Sanders's speech, they celebrated by declaring their solidarity with his still-running campaign.

"The room was silent, because we realized what a profound movement it was," DeMoro said. "Then we sang karaoke. The first group was the VA nurses, and they sang 'My Guy.' You know: 'Nothing you can say will take me away from my guy.' And the next group sang 'Don’t Stop Believing.' It was heartwarming."