"When you say Bernie or bust, that means if we don't get Bernie, we're just not going to automatically vote for the demon because you're saying the devil may be there," said Billy Taylor, who is organizing a coalition of Bernie Sanders supporters to protest at the Democratic convention here in July.
Sanders has inspired a movement, but it's unclear whether he can control it. Or if he wants to.
After the final wave of states vote next Tuesday, Sanders has one decision to make. His supporters have another. And many insist they will not fall into line behind Hillary Clinton.
"You can't expose the corruption of the political system and then expect us to get behind that same political system," said Gary Frazier, a leader of a group called Black Men for Bernie, who is also organizing Sanders supporters here in Philadelphia.
In interviews here this week, Frazier and Taylor outlined their plans to CNN, imploring Sanders' supporters to leave the Democratic Party to protest rules governing the presidential nominating system. They are taking seriously Sanders' call for a political revolution, complicating any hope for quick unity with Clinton.
"We are prepared to de-register from the Democratic Party and explore other options. Maybe we don't get it done in this election, but I can damn well guarantee you this: We mean business," Frazier said. "If Bernie Sanders does not walk out of that thing as the nominee, we can guarantee you from that point on we'll start the de-registration of the Democratic Party. They have a choice to make."
Their passion doesn't change the hard reality of the delegate math: Clinton will clinch the party's nomination next Tuesday. Sanders will not.
Yet Sanders' most loyal supporters are now convinced the system is rigged, setting up a collision course for Democrats. He has done little to dissuade them.
"It's an unfair system, it's a dumb system, and it's a system we will change," Sanders said in California, rallying supporters through comments that have fueled deep skepticism about party rules.
The support for Sanders is not built on the party faithful alone.
CNN exit polls from 27 states that have voted this year show that 63% of Sanders' supporters are Democrats and 33% are independents or from another party. It's a far cry from Clinton, whose supporters are 85% Democrat and only 13% independent or from another party.
Clinton needs some of those independents to win, which is why winning over those Sanders supporters is critical to her campaign.
"He said the other day he'll do everything possible to defeat Donald Trump," Clinton told CNN's Jake Tapper on Tuesday. "I take him at his word. The threat he poses the country and democracy and economy, I certainly expect Senator Sanders to do what he said he would."
The Clinton campaign is also counting on Trump to serve as a unifying force to the party, which is a miscalculation in the minds of Taylor and Frazier.
"If we don't go along with Hillary, then Trump's going to get the presidency and the world's going to be in shambles," Frazier said. "That's 'BS' to us."
A Quinnipiac poll Wednesday found that 75% of Sanders supporters said they would rally behind Clinton in a race with Trump, but about a quarter of his supporters went elsewhere. It's an open question whether the campaign's heat of the moment will fade or give way to party unity.
Sara Alicia Huerta Long, who traveled to New Jersey from Michigan to volunteer for the Sanders campaign, said she believed the "Bernie or Bust" movement had considerable support and Clinton would struggle to win over Sanders' supporters.
"There's a lot of first time voters who've only come out to vote for him," Long said in an interview, "and they don't want her."