Michigan Democratic Rep. John Conyers has been introducing his single-payer health care bill for decades. But in the explosion of activism following the Bernie Sanders campaign and the pushback against GOP efforts to repeal parts of the Affordable Care Act, his bill HR 676 has suddenly become much more popular. It now has the support of the majority of the House Democratic caucus.

Last month, a group of activists with the Metro DC Democratic Socialists of America turned its sights to Virginia Rep. Don Beyer, one of the Democrats who had yet to sign onto HR 676.

They started their lobbying by calling Beyer’s office, said James McCormack, an activist with the Northern Virginia chapter of the Metro DC DSA.

“It was never something like ‘we don’t like the bill.’ It was always just, ‘We are looking into it. We’re studying it further,'” McCormack told The Intercept about the response from the congressman’s office.

When that didn’t work, they came up with a plan to directly confront Beyer. Numerous DSA members attended a September 17 town hall Beyer held, sharing their health care horror stories and asking the representative to sponsor the Conyers bill that would establish a universal health care system.

At first, Beyer was hesitant, telling the activists that there are “many problems with the legislation.” But after five activists took turns at the microphone asking Beyer to sponsor the legislation, he relented and announced his intention to sign on. On September 26, he was officially added as a co-sponsor to HR 676.

Beyer has “long supported universal healthcare and the idea of a single payer system,” said Press Secretary Aaron Fritschner, but he has also had some concerns about the Conyers bill, “including the need for greater specificity on how we pay for an expansion of Medicare, the timeline for the transition period, and how much decision-making we leave in the hands of the Secretary of Health and Human Services.”

Still, after hearing “the strong and heartfelt requests from his constituents,” Beyer agreed to cosponsor the bill since he supports its broad objectives, Fritschner told The Intercept, adding that the congressman supports other legislation that expand health care coverage, including the bipartisan Murray-Alexander bill.

The success was a real teaching moment for the DSA.

“It was our first real campaign as a branch together,” McCormack said in an interview. “This is a win for us, unequivocally”

Watch this short documentary about how DSA won Beyer’s support: