Minnesota Attorney General Keith Ellison, a surrogate for Sen. Bernie Sanders (I-Vt.), sought to defend the presidential candidate’s supporters by asking on Twitter for examples of a bad-acting “Bernie Bro.”

“I can think of an example,” House Minority Whip Steve Scalise (R-La.) wrote back.

Scalise was alluding to the Sanders supporter who in 2017 opened fire on a congressional Republican baseball practice, severely wounding the congressman and striking four others. The shooter had railed against President Trump and Republicans on social media and volunteered on Sanders’s 2016 presidential campaign.

Sanders said in a statement at the time that he was “sickened by this despicable act.”

But there remain a subset of Sanders supporters known as “Bernie Bros” who operate as online trolls, using hostile and vitriolic language and threats against people who publicly challenge Sanders. Most recently, when leaders of the Culinary Workers Union in Nevada criticized Sanders’s Medicare-for-all plan, they reported receiving harassing messages.

The subject came up in Wednesday night’s debate, when former South Bend, Ind., mayor Pete Buttigieg implied that Sanders was responsible for the behavior of his supporters.

“At a certain point, you got to ask yourself, why did this pattern arise? Why is it especially the case among your supporters that this happens?” Buttigieg posed to Sanders.

Sanders, who has disavowed the attacks repeatedly, pushed back, saying that women on his staff are also subject to “disgusting” attacks, suggesting that the “Bernie Bros” could be Russian disinformation bots and calling it “not thinkable” that any real supporter of his agenda would attack union leaders.

“But leadership is about what you draw out of people. It’s what — it’s about how you inspire people to act,” Buttigieg replied.

It was that exchange that inspired Ellison to tweet in defense of Sanders’s supporters Wednesday night.

“I have never seen @BernieSanders supporters being unusually mean or rude,” Ellison tweeted. “Can someone send me an example of a ‘Bernie Bro’ being bad. Also, are we holding all candidates responsible for the behavior of some of their supporters? Waiting to hear.”

The reaction on Twitter, as is often the case, was swift and divided. Many, including Scalise, were quick to remind Ellison of the Sanders supporter who tried to kill Republicans. Others, including Democrats, offered examples of times they’d been attacked by people on social media who purport to support Sanders.