Bernie Sanders’ speech at the People’s Summit in Chicago on Saturday will mark a “turning point” for the political revolution he inspired, according to the organizers behind the three-day activist event.

Sanders will headline the event on Saturday night, while high-profile celebrity activists including Mark Ruffalo, Jessie Eisenberg and Naomi Klein will also attend.

Some of the most influential progressive organizations in the country – representing millions of people – are behind the summit, including People for Bernie, National Nurses United and the Sanders-backed Our Revolution.

“It’s going to be a turning point for the people who have been really invested in the Bernie revolution,” said Winnie Wong, a key organizer of the summit and a co-founder of People for Bernie, an independent group with more than a million members who supported his bid for president.

Wong said the summit would be a “political education for organizers ahead of 2018”.

“They will be better prepared to create campaigns that are authentic and credible and principled. The program is conceived to make sure that people leave with a plan.”

Some of the sessions at McCormick Place will focus specifically on training progressives to run for office or organize campaigns ahead of the 2018 midterms. Sanders’ wife, Jane, on Wednesday launched the Sanders Institute, a not-for-profit group that aims to educate people on progressive issues, and the institute will organize events bringing people from each of the 50 states together to plan campaigns.

Among the most anticipated speakers will be “Berniecrats” who have recently won office running on a Sanders-esque message.

Khalid Kamau, a self-identified democratic socialist who became one of the first Black Lives Matter activists to hold elected office when he won a seat on Atlanta’s South Fulton city council in April, will host a session called Down-Ballot Revolutionaries.

State assemblywoman Christine Pellegrino, a Sanders delegate who became the first ever Democrat to represent New York state’s ninth district when she won a special election in May, will also speak about her success.

Both Pellegrino and Kamau were endorsed by Our Revolution and People for Bernie, and supporters of those groups canvassed and made phone calls on their behalf, in a template progressives hope can serve other candidates in the 2018 mid-terms.

“That pulled progressives from all over New York state,” Pellegrino said of the endorsement. “It was a real hotbed for activism, and our campaign gave progressives something to really dig into.”

Pellegrino said her victory shows that Democrats “should run truly progressive candidates in every race up and down the ticket”.

A Sanders supporter. Photograph: Dominick Reuter/Reuters

Even with the support of activist-led organizations, Pellegrino said she could not have won without the financial support of the more establishment-oriented Nassau County Democratic party – a warning to progressive candidates across the country.

“You can’t underestimate the necessity of financial backing,” she said. “We’ve been saying as progressives we wish it didn’t have to be this way, but a campaign is an organization that has people. And those people need to be provided with the resources that they need.”

A key to her win, Pellegrino said, was that “we knocked on doors where people said they had never been spoken to” by Democrats.

“When you ignore voters for years and years and years, how can you expect them to turn out?”

One of the organizations holding events at the summit specifically focuses on this kind of outreach. Knock Every Door, which was formed in January, recruits and trains volunteers to canvas potential voters.

Becky Bond, a former senior adviser to the Sanders campaign and part of the team that runs Knock Every Door, said winning voters is about “talking to everybody”, not just Democratic voters, in an effort to have what Bond called “listening conversations” on the doorstep – not just delivering a sales pitch.

“When someone feels listened to, they’re much more likely to engage back with you,” Bond said. “There’s been a lot of research behind this. If you just go to the door and deliver a script that’ll have some effect.

“But if you actually have a back and forth conversation with someone, that’s how people change their thinking.”

Bond, who will lead a “big organizing beyond Bernie” seminar this weekend, said Democrats and progressives can learn from the Trump campaign.

“If you look at the Trump phenomenon, a lot of people felt Trump understood what was going on in their lives.

“Obviously Trump was lying about what he was going to do to help people, but the fact that they felt like he saw them and recognized their situation is really, really important.

“And one of the ways that we do that is by listening to people at the doors before we start talking to them about our experience and how that leads us to different conclusions.”

This is the second People’s Summit, following the inaugural event last year. Six organizations – People’s Action, Democratic Socialists of America, Our Revolution, National Nurses United, People for Bernie and Progressive Democrats of America – have spent months organizing the three-day program, and Wong said 45% of the attendees will be younger than 35.

Kamau, the newly elected South Fulton councilman, said part of the focus of his down-ballot revolutionaries seminar will be getting those under-35s into office.

“It’s about building a bench,” Kamau said, pointing out that high-profile, young Democrats are few and far between.

“Getting young people to first run for city council, then state house, then congress, then governor.”

Kamau campaigned on a platform that included raising the minimum wage to $15 an hour, ending “money for bail”, making voting day a holiday and decriminalising marijuana.

“People think that stuff will never work here in Georgia. But if you can get it to work here then you can scale it up to a national level,” Kamau said.

The Democratic party “are scared about a national minimum wage, and about decriminalizing marijuana”, he said.

“But if you can do it a local level then it becomes like a domino effect. Because when people see that it works in one place and this guy doesn’t fall, then they will try it in other places, and larger places.”

Larry Krasner will co-host the down ballot revolutionaries session with Kamau. Krasner won the Democratic primary for Philadelphia district attorney in May, defeating a host of establishment candidates. In a heavily Democratic city, he is extremely likely to take office in November.

While Pellegrino won with support of the local Democratic party, Krasner ran much more of an insurgent campaign without establishment support – his victory serving to show that there is more than one way to skin a cat, but also serving as a warning to the Democratic party elite as a whole.

Krasner, a Sanders supporter in 2016, pledged never to pursue the death penalty, to work to end mass-incarceration, and to treat drug addiction “as a medical addiction rather than a crime”.

He received party support in only 12 city wards out of 66, but despite this won 47 of those wards to receive the nomination.

“The Democratic party has a choice,” Krasner said.

“They can remain a party that is accustomed to having people with the same last name run, in which case they look just like the Republican party and the Bushes.

“They can be a party dominated by career politicians doing things in ways that may be outdated, they can fight the progressives, or they can get smart.”

Krasner said achieving that smartness means embracing the left.

“Running towards the center is not always the best plan. Sometimes increasing the tent is the better plan.”

Organizers hope that the People’s Summit can go some way towards expanding that tent ahead of 2018.