In September, Sanders himself had to tweet he was opposed to “racist bullying and harassment” after some backers besieged the Working Families Party for endorsing Warren, whose advisers contend that marked the beginning of aggression against her from Sanders’ partisans.

That hostility increased after POLITICO reported last week that Sanders’ field staff was using unflattering talking points to describe Warren.

Warren’s account of the private 2018 one-on-one conversation between them appeared in the media not long afterwards.

Asked about it onstage during Tuesday’s debate, Sanders denied he made the remarks. When a CNN debate moderator then asked Warren for her version of events, framing the question in such a way that it accepted her version of events as true, some Sanders supporters insisted the fix was in. After all, CNN broke the story about the remarks just before hosting its debate, ensuring maximum impact.

Following the debate, Sanders’ campaign co-chair, Nina Turner, fumed to reporters about “faux feminism.” Online, other supporters called Warren a liar and brought up her misrepresentations about her Native American ancestry. And they pointed out that Sanders — who has publicly advocated for women to be president for years — received more money from women donors than any other Democrat.

Still others complained that Warren has never attacked Biden over abortion and his support of a widely derided bankruptcy bill, a longstanding point of contention between them. Instead, Sanders’ supporters note, Warren attacked Sanders in a potentially devastating way in a progressive primary.

A top Warren aide privately said there’s no backroom deal with Biden and accused the Sanders campaign of hypocritically dishing out campaign attacks and then whining when she hits back.

Karen Finney, a senior Clinton adviser, said she’s familiar with the reaction of Sanders supporters who rally when Sanders is attacked, especially considering how the topic that played out this week. “[T]here seems to be an element of sexism, grievance and Bernie is fighting for them,” she said.

Democratic women have reacted viscerally to the condemnation of Warren by Sanders backers because it reminds them so much of what happened four years ago, Finney said.

“This time they’re not going to let the Bernie Bros do what they did last time,” she said. “There’s resentment still. There’s a scar there. And the wound reopened.”

Alex Thompson contributed to this report.

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