One of the big questions in the debate over Sen. Bernie Sanders’s angry online fans is whether they’re worth talking about at all. They don’t speak for the campaign, so it’s unfair to blame Sanders for their antics. And the vast bulk of the American public isn’t on Twitter — why would you expect them to base their vote on what happens on that site?

Sen. Elizabeth Warren’s campaign exit interview with Rachel Maddow, aired Thursday night, is a clarifying moment in this conversation. In the interview, Warren showed palpable anger with the online Sanders army’s treatment of her and other progressives.

“I think there’s a real problem with online bullying and online nastiness. I’m not just talking about who said mean things; I’m talking about some really ugly stuff that went on,” she said. She expressed particular concerned about threats, citing the publication of phone numbers and home addresses belonging to two women who worked for the Nevada Culinary Union after it produced a fact sheet critical of Sanders’s health care plan.

Warren’s reaction illustrates that these tactics make it at least somewhat harder for Sanders to build allies in the Democratic Party. And this failure of elite backing has real repercussions.

Maddow asked about Sanders’s disavowal of his supporters’ attacks on her, and Warren seemed not to find it very persuasive. “We are responsible for the people who claim to be our supporters and do really dangerous, threatening things to other candidates,” Warren said. Then when asked if “it’s a particular problem with Sanders supporters,” the senator replies bluntly: “It is. And it just is. It’s just a factual question.”

It’s worth watching the clip to get a sense of how deeply frustrating this is for Warren. She starts off by talking about her long friendship with Sanders, how much respect she has for him. And then she pivots to an emotional discussion of online harassment; you can hear that it’s clearly shaped her perception of the race:

You can understand why Warren seems to think Sanders’s disavowals ring a bit hollow. Sanders sat down for an interview with Chapo Trap House, the “dirtbag left” podcast whose hosts repeatedly serve up some of the most vicious and personal attacks on Warren. Sanders speechwriter David Sirota has appeared on their show while working on the campaign, as has national press secretary Briahna Joy Gray. From Warren’s point of view, it might seem like Sanders is speaking out of both sides of his mouth: vaguely disavowing online anger in public statements while his campaign reaches out and appeals directly to the people purveying it.

The purported aim of all the pro-Sanders trolling, the snake emojis directed at Warren on Twitter, and the vitriolic attacks on the Nevada Culinary Union is to shame or bully the targets into getting behind Sanders. Judging by this interview, it seems to have had the opposite effect on Warren.

Online anger and abuse may not filter down to the ordinary voter directly, but it shapes the way Democratic Party elites see the Sanders campaign. If they see it as a font of negativity and anger or a source of direct attacks on them and people they admire, they’re less likely to see it as something they’re comfortable lining up behind. And these sorts of endorsements can matter in primaries; support from Rep. Jim Clyburn (D-SC) and Sen. Amy Klobuchar (D-MN) seems to have really helped buoy Joe Biden in their respective states.

Fundamentally, if Sanders and his movement want to succeed in remaking the Democratic Party in their image, they can’t just drive out every person in a position of power right now. To go from insurgents to party leaders, they need to figure out a way to court the people with influence in the party. Right now, it seems to be the case that the pro-Sanders online brigades are making that harder.

You can call this childish if you want; that Warren and other Democratic elites are letting hurt feelings get in the way of progressive politics. But it doesn’t change the fact that they sincerely believe this is important — and no number of snake emojis is going to change their mind. If Sanders’s fans are really serious about helping their guy, they need to think carefully about whether what they’re doing is actually working.