Wivell’s words pinpoint the exact reason many Sanders supporters still prefer the Vermont lawmaker to Senator Elizabeth Warren of Massachusetts, the 2020 candidate who aligns most closely with Sanders ideologically and who, like Sanders, has proposed a number of ambitious progressive proposals. While on a policy level, the two senators are quite similar, there is still a clear and important difference between them, argued the DSA members I spoke with: Sanders is fighting for a political revolution. Warren isn’t.

Right as the debate began, I pulled up a stool next to John Kastronis, a 37-year-old technical writer from nearby Arlington, Virginia, who was wearing a graphic tee with a picture of Karl Marx riding a skateboard. Kastronis, who told me that “the past couple of years have really pushed me into the socialist mind-set,” said he admires Warren’s knowledge and passion, but Sanders, whose 2016 campaign paved the way for so much of the policy discussion under way in the current primary, is still the “most progressive one in the room.”

When Warren delivered her opening statement at the start of the debate, the group listened politely. Some people clapped. But when it was Sanders’s turn, they whooped and hollered. One person in the back yelled, “Yes, Dad!” They pounded the bar to show their support as Sanders rattled off statistics about health insurance and homelessness, and called out Amazon for not paying federal income taxes.

“See? There’s a difference!” Kastronis said, whipping around in his seat to face me. “He’s calling out specific companies and specific people, whereas Warren said more feel-goody stuff.”

Sanders and Warren are both grassroots progressives with clear populist streaks, and both are pushing for massive reforms, with a particular focus on income inequality: Warren’s 2020 stump speeches always include a line about how the economy is “doing great” for only a thin slice of Americans, and Sanders has been railing against the wealth of America’s “top 1 percent” for years. But their political philosophies offer a stark difference: Sanders, a self-described democratic socialist who is not an official member of the DSA, views capitalism as unjust, while Warren has called herself a “capitalist to my bones.” Steadfastly refusing to join the Democratic Party, Sanders has embraced and even treasured his status as an insurgent candidate, while Warren, throughout her political career, has worked more closely with the party establishment—more intent on building bridges than burning them.

Group members explained to me that Warren, with her myriad plans for addressing the country’s biggest problems, is operating under the false premise that good laws can fix an inherently broken system.

“It’s not that her policies are bad—it’s just that her stuff would work [better] in a system that wasn’t a failed state,” said Irene Koo, a 24-year-old editor at the Center for American Progress, a liberal think tank. In other words, it’s too late for Warren’s plans. The movement Sanders is building, members told me, aims to overturn that system and inspire a new generation of political leaders. They referenced up-and-comers such as Representative Alexandria Ocasio-Cortez of New York; Tiffany Cabán, the former district-attorney candidate in Queens County, New York; and Vincent Fort, the Georgia state senator. Compared with Warren, Koo said, Sanders has a “very evidently different theory of change.”