Bernie Sanders inspired millions of people during his presidential run. But even some of his supporters wondered how he’d have any shot of enacting his progressive agenda through Congress if he won. Sanders’s answer was that a grassroots people’s movement–the same that would get him elected–would need to continue.

“What the campaign showed us was that you could out-raise a well-funded opponent with grassroots donations, and you could out-voter-contact them, too.”

This week, Sanders told his supporters that the top priority of the next few months will be to defeat Trump, even though he has lost the nomination. But he also called on his supporters to continue what he started by fighting in other local, state, and federal races. A number of candidates for lower offices have even self-identified as “Berniecrats.”

Even though Sanders won’t be president, some of his former staffers and campaign volunteers are organizing to continue his agenda by turning their focus to Congress.

Brand New Congress is an ambitious campaign that seeks to use the same grassroots organizing tactics to back a “slate” of 535 candidates for the House of Representatives and Senate in the 2018 midterm elections.

“What the Bernie campaign showed us was that you could out-raise a well-funded opponent with grassroots donations, and you could out-voter-contact them, too,” says Saikat Chakrabarti, Sanders’s former director of organizing technology. “But it only works if you can concentrate all of these dispersed people onto one goal and focus it.”

So far Brand New Congress is run by about a dozen all-volunteer teams, with about 100 people doing work every day, says Chakrabarti. Many people supporting it include regional and local volunteer organizers for the Sanders campaign, such as Moumita Ahmed, a lead organizer for Millennials for Bernie, as well as some of his campaign staff, such as senior adviser Zack Exley.

“The power of Bernie Sanders was not only in his email list,” says Chakrabarti. ”The centers of power were local groups that formed on Facebook and Reddit.”