Conservative leaders declared war on the ethno-nationalist “alt-right” Thursday, tossing one of that movement’s top figures out of the Conservative Political Action Conference, saying they don’t want their causes tainted by racist, sexist or anti-Semitic messages.

The forceful denunciation of the alt-right from the CPAC stage and the ousting of alt-right leader Richard Spencer seemed designed to establish boundaries for who is welcome under the conservative tent — and who is not.

“CPAC, we have been slapped in the face,” Dan Schneider, executive director of the American Conservative Union, said as he kicked off the three-day gathering. “There is a sinister organization that is trying to worm its way in, into our ranks.”

The conservative movement’s identity has been shaken by the rise of President Trump, whose campaign was criticized for appearing to tap into some of the same sentiments that fuel the alt-right, a loose fringe coalition that claims to be the leading edge of right-wing thought. Though there are a number of strands of alt-right, a common theme is fealty to a “white identity” that needs boosting in modern American culture.

Mr. Schneider said it was a “hate-filled, left-wing fascist group” that needed to be drummed out of conservative gatherings.

“We must not be duped. We must not be deceived,” he said.

The fight is similar to the purge led by William F. Buckley in the 1960s, when he forcefully denounced the John Birch Society and Ayn Rand’s followers, saying they didn’t represent the emerging conservative movement.

“The basic idea was that Buckley wanted conservatism to be a responsible and respectable kind of ideology. He wanted conservatives to be able to win elections,” said Geoffrey Kabaservice, author of “Rule and Ruin,” a book chronicling the Republican Party’s modern history.

Buckley referred to the fringe groups as “kooks” and said conservatives couldn’t afford to be associated with movements defined by conspiracy theorists, racists and neo-Nazis.

Today, modern conservatism’s leaders find themselves facing the same challenge — though there isn’t anyone with the status of Buckley to enforce the redefining.

“The question is, given the fact that there aren’t figures with the kind of authority of Buckley or [Ronald] Reagan, how effective is it going to be?” Mr. Kabaservice said.

He said the challenge is even tougher with the emergence of Stephen K. Bannon, counselor to the White House and former chief at Breitbart News, an outlet for alt-right debate. Mr. Kabaservice said nobody from the John Birch Society ever served in a high office in the White House.

In years past, Breitbart hosted sessions on the fringe of CPAC dubbed the “Uninvited,” where figures who weren’t given slots on stage by CPAC organizers were able to speak.

Mr. Bannon, from the main stage Thursday, joked about those years on the outside.

“I want to thank you for finally inviting me to CPAC,” he told Matt Schlapp, chairman of the American Conservative Union, which serves as host of the annual gathering. “I know there are many alumni [of Uninvited] out here in the audience.”

Mr. Schlapp said CPAC was trying to bring those folks inside.

“We decided to say that everybody’s a part of our conservative family,” he said.

That wasn’t the case, however, for Mr. Spencer.

The popularizer of the term alt-right showed up Thursday and paid for a general admission ticket. When he got inside, he held forth with reporters, drawing attention — and the boot from organizers.

“He’s not welcome here,” said Ian Walters, a spokesman for the American Conservative Union.

“It’s sort of media pranksterism but a very dangerous kind that involves hateful rhetoric,” Mr. Walters said. “There’s no place for that here. There’s no room for that here.”

Howard “Cowboy” Wooldridge, a retired police detective and a lobbyist on Capitol Hill on drug policy issues, said the movement has nothing to do with the conservative point of view.

“This is one-tenth of 1 percent just completely out to lunch, whatever you want to call it,” he said. “It was good that they condemned it. It’s good that they’re saying, ‘We ain’t got nothing to do with those folks.’ “

CPAC earlier this week also disinvited alt-right provocateur Milo Yiannopoulos from its speaker’s list after videos emerged last weekend of him appearing to condone pedophilia, saying sex between 20-something adults and 13-year-old children sometimes happens “perfectly consensually.”

Mr. Yiannopoulos also resigned as an editor at Breitbart and had a book deal canceled.

John Baker, who traveled to CPAC from South Carolina, told The Washington Times that he was relieved that CPAC withdrew the invitation.

“It would have been more of a distraction and a media frenzy, and there are much more important things that we need to be looking at,” Mr. Baker said.

Alan Arnold of Sarasota, Florida, said he thinks Mr. Yiannopoulos is just a “shock jock.”

“I think he represents himself and his own little projects, and I think one of his goals is to shock,” Mr. Arnold said. “I don’t think it follows the Republican Party’s program.”

But Scottie Nell Semler Hughes, a former campaign surrogate for Mr. Trump, said CPAC lost an opportunity because of the work Mr. Yiannopoulos had done to spread aspects of the Republican Party’s message to universities during the campaign season.

“For once, we were having a real conversation on our college campus and exposing the liberal hypocrisy of conservatives who have been bullied into silence on it,” she said.

Kathleen Smero from Baltimore said she thought it was hypocritical for CPAC to disinvite Mr. Yiannopoulos.

“We’re all up in arms that Berkeley and all these other universities are so against him and don’t want him to speak, and yet we wouldn’t allow him to speak here,” she said. “If there were something that had to be cleared up in his book or in his life, then he had an opportunity to address it and we had an opportunity to listen.”

• Stephen Dinan contributed to this report.

Sign up for Daily Newsletters Manage Newsletters

Copyright © 2020 The Washington Times, LLC. Click here for reprint permission.