Donald Trump speaks during an Oct. 29 campaign event in Phoenix. (Carlo Allegri/Reuters)

Donald Trump’s campaign manager on Sunday forcefully disavowed a supporter as “deplorable” for chanting “Jew-S-A!” at a weekend rally, the latest incident of anti-Semitic rhetoric used by some of the GOP nominee’s backers.

“[The man’s] conduct is completely unacceptable and does not reflect our campaign or our candidate. Wow,” Kellyanne Conway said during an interview on CNN’s “State of the Union.” “That man’s conduct was deplorable. And had I been there, I would have asked security to remove him immediately.”

The Saturday afternoon incident in Phoenix, which was captured on video, revived long-standing anxieties about xenophobic and white supremacist rhetoric used by a fringe faction within the GOP nominee’s base. A man confronted reporters at the rally with shouts and a three-fingered hand gesture that resembled hate symbols flagged by the Anti-Defamation League.

“You’re going down! You’re the enemy!” the man yelled. As the rest of the crowd broke into a chant of “USA! USA!,” the man repeatedly chanted, “Jew-S-A! Jew-S-A!”

Kellyanne Conway, shown here after the last presidential debate, said a Trump supporter who shouted an anti-Semitic chant at a Trump rally is “deplorable.” (Lucy Nicholson/Reuters)

The man, who wore a “Hillary for Prison” T-shirt, asserted that Jews control the media, a common theme among white supremacists.

The man identified himself as George Lindell, according to the Arizona Republic; the newspaper noted that he achieved “viral notoriety” after a local television interview in 2011 in which he described a car accident he was involved in.

Conway agreed on Sunday when CNN’s Jake Tapper asked whether the man’s behavior was “deplorable” — a reference to controversial comments made last month by Democratic nominee Hillary Clinton, who was criticized for casting “half of Trump’s supporters” as a “basket of deplorables.” Clinton later expressed regret for suggesting that half of his supporters were racist or xenophobic.

Conway said “tens of thousands” of supporters gather at rallies who do not engage in such behavior.

“And these are USA-loving Americans who just want their country to be prosperous and safe again,” she said.

Anti-Semitic slogans and language have become common among self-identified members of the “alt-right,” a fringe conservative movement that fashions itself as a populist and anti-establishment alternative to the mainstream Republican Party. Many within the alt-right have enthusiastically embraced Trump’s campaign message, which has included calls for mass deportations of undocumented Latino immigrants and for barring foreign Muslims from entering the United States.

Many of Trump’s critics have accused him and his campaign of stoking racial grievances as a political tool. Those accusations have intensified since Stephen K. Bannon stepped away from running Breitbart News — which he has called a “platform for the alt-right” — to become the Trump campaign’s chief executive.

“I wouldn’t want to tar and feather every Trump supporter with the anti-Semitic comments of one person, but it is the case that the Trump campaign has been embraced by the radical right in an unprecedented way this season,” said Richard Cohen, president of the Southern Poverty Law Center.

Cohen added that he has been troubled by Trump’s embrace of the alt-right and pointed to Bannon’s role on the campaign in particular, but he added that Conway did the right thing in disavowing Saturday night’s chant. He said white supremacists like former Ku Klux Klan leader David Duke who embrace Trump — and Trump’s often lackluster disavowals of those endorsements — “say something about the man.”

“Look, I don’t want to comment on the machinations of the campaign. Miss Conway seems like a smart cookie, and she said the right thing,” Cohen said. “I think Trump has been slow to distance himself from the radical right and in fact he seems to embrace the person who has created a platform for them online.”

Jonathan Greenblatt, the ADL’s director and chief executive, said that Conway’s response Sunday was a positive step for the campaign. But he said he remained troubled by the pervasiveness of such rhetoric.

“It’s troubling in the first place that someone would feel comfortable to spout anti-Semitism at a political rally. But we’re heartened that Kellyanne Conway immediately spoke out in a clear and forceful manner,” Greenblatt said.

“Too often intolerance has been given a pass during this campaign, so this was an important step,” Greenblatt added. “We hope this approach of quickly condemning hate will be the new norm for the candidates and for all public figures, not just in the remaining days of the campaign, but in the future long after this election.”

Greenblatt has raised concerns about the rise of anti-Semitic language among Trump supporters in the past, expressing fears that Trump’s speeches have at times carried tropes and stereotypes that have been historically used to demonize Jewish people. Greenblatt said that Trump’s claims in a speech earlier this month that “a global banking elite are trying to destroy U.S. sovereignty” was reminiscent of historical anti-Semitic language.

“I’m not saying that the candidate is intentionally doing this, but whether it’s the speechwriters or his supporters, we’re seeing tropes and stereotypes about Jews dominating the global banking system,” Greenblatt said after that speech.

Trump came under fire over the summer for retweeting an image of rival Hillary Clinton alongside $100 bills and a Jewish star bearing the words “most corrupt candidate ever!” Trump later claimed that it was a sheriff’s star.

Trump’s son, Donald Jr., also drew attention for doing an interview with a white-nationalist radio host this year; he later told Bloomberg News that he did not realize the interviewer was going to be looped into the conversation. He was also blasted for posting an image on social media he said he got from a friend that included Pepe the Frog, a figure that has been appropriated by white supremacists. He told ABC News that he did not know about the association.

Trump routinely bashes members of the news media at his rallies, labeling them “dishonest” people who are part of a “rigged” system that he claims is working against him. The crowd usually piles on with boos. In recent weeks, Trump has intensified his anti-media rhetoric at his rallies. His crowds have followed his lead, booing and taunting reporters when the GOP presidential nominee complains about the press.

Sullivan reported from Phoenix.