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Bernie Sanders was put on the spot at the Democratic debate Wednesday night over the vicious online attacks by some of his online supporters. Sanders bluntly condemned their behavior.

“We have more than 10.6 million people on Twitter, and 99.9 percent of them are decent human beings,” Sanders said. “If there are a few people who make ugly remarks, I disown those people.”

“They are not part of our movement,” he concluded.

The moderators of Wednesday’s Democratic debate in Nevada asked @BernieSanders about the vicious online attacks by some of his online supporters. He disowned those people: "They are not part of our movement.” pic.twitter.com/SOVX90PSPS — Mother Jones (@MotherJones) February 20, 2020

Sanders’ comments came after former South Bend, Indiana, Mayor Pete Buttigieg reminded viewers that Sanders supporters had threatened top officials of Nevada’s Culinary Union, a Democratic powerhouse, over the phone and online in the lead-up to Saturday’s Nevada caucuses, the third nominating contest of the Democratic primary. (The union has recently warned its members about Sanders’ Medicare-for-All plan.)

Buttigieg seized on Sanders’ response, suggesting the senator was showing a lack of personal responsibility. Buttigieg said he respected what Sanders’ said, but wondered, “At a certain point, you gotta ask yourself: Why did this pattern arise? Why is this especially the case among your supporters?”

Sanders vehemently disagreed, adding that his campaign surrogates like former Ohio state senator Nina Turner have also been the subject of “ugly, sexist, racist attacks.”

Buttigieg pushed back: “It’s about how you inspire people to act. I think you have to accept some responsibility.”

Sanders’ online supporters have been a source of fascination and derision throughout the campaign, earning particular scrutiny after the behavior toward the Culinary Union leaders came to light. Earlier this week, former New York Mayor Michael Bloomberg released an ad featuring a supercut of some of Sanders’ supporters most stunning barbs. Sanders already condemned that behavior during a CNN town hall on Tuesday night, telling an audience that he doesn’t tolerate “ugly attacks against anybody.”

“I have an idea about how you stop sexism on the internet,” Minnesota Sen. Amy Klobuchar volunteered after the exchange Wednesday. “Nominate a woman.” Yeah, sure, that’ll solve it, Amy.