While president-elect Donald Trump's transition team did not respond to a request for comment, advocacy groups say Bannon's appointment to the highly influential post in the incoming administration is a cause for concern.
"It is a sad day when a man who presided over the premier website of the alt-right, a loose-knit group of white nationalists and unabashed anti-Semites and racists - is slated to be a senior staff member in the 'people's house,'" said Jonathan Greenblatt, CEO of the Anti-Defamation League, in a statement.
Among those calling to give Bannon a chance, however, is Reince Priebus, the former Republican National Committee chair whom Trump newly christened as his chief of staff.
Priebus called Bannon smart and temperate.
"The guy I know is a guy that isn't any of those things," Priebus told NBC's "Today” on Monday.
To understand the current climate and the rise of the alt-right movement, Levin offered some historical perspective. He compared the current political upheaval to the 1920s, when the United States emerged from World War I and transitioned from an agrarian to an industrial economy. There was a "populist angst" at the time, Levin said, over the decline of culture brought about by jazz, alcohol and massive Catholic immigration from Europe.
Now, there's been both a demographic shift and a cultural shift, marked by the Supreme Court’s seminal ruling on gay marriage, the growth of the transgender-rights movement and greater legalization of marijuana.
"It sounds a lot like the 20s," Levin said.
While the U.S. population of whites declines, Levin noted, so too has the number of jobs available to whites who didn’t go to college. Meanwhile their mortality rates have spiked.
"So today we have a disquieted group that feels disenfranchised,” he said. “And they're concerned about their personal future but also the changing demographics, culture and mores of the country. They don't feel that they've been heard."
Despite “the bigotry that is found in its most fringe areas,” Levin said, the alt-right also enjoys broad appeal.
Breitbart senior editor Milo Yiannopoulos touched on these themes in an article back in March. Gay and British, Yiannopoulos is one of the alt-right’s most popular voices.
"For decades, the concerns of those who cherish Western culture have been openly ridiculed and dismissed as racist,” Yiannopoulos wrote. “The alt-right is the inevitable result. No matter how silly, irrational, tribal or even hateful the establishment may think the alt-right’s concerns are, they can’t be ignored, because they aren’t going anywhere."
Yiannopoulos did not return a request to be interviewed for this article.
Levin said the alt-right wants to deconstruct political and social institutions perceived as repressive, including the Republican and Democratic parties. Though he acknowledged the broad appeal of the movement, he said the fringe areas have worked their way into the mainstream.
Bannon, while at the helm of Breitbart, helped them do it, Levin said.
When Bannon took over Breitbart, he retooled the conservative website so that it would appeal to fringe elements in the alt-right "in a very coarse and prejudicial manner," Levin said. The website helped coalesce the alt-right movement through fear mongering, with a focus on black crime, Muslim extremism and the idea that Muslims are treasonous.
"He didn't invent this stuff,” Levin said. “But he took the parts, put them together and drove it to where it wanted to go."
Levin called this "worrisome."
"I'm not calling him a hard-core hate monger or a leader of a hate group,” Levin said of Bannon. “What I am saying is, his boot-strapping of the messages, which came from the extreme, amplified and directed a whole cadre of umbrella groups in the alt-right to believe that they had a leader.”
In the past, people from the Aryan Nation, the National Alliance or the Ku Klux Klan failed to effectively reach out to the mainstream, largely because of the baggage of being deemed hate groups, Levin noted.
"But if someone who has achieved success and notoriety and respect echoes those same messages, and retransmits them into the mainstream, that's extraordinarily powerful," he said. "Because those messages will have a legitimacy that they wouldn't have from a messenger that's less accessible."
There could be long-term effects, Levin cautioned.
"The problem is when this toxicity is unleashed into our sociopolitical water supply, it's addictive, corrosive and long-standing – even if the person who's exploiting it isn't necessarily as hardened in their policy positions as their rhetoric might indicate,” he said.
In a normal year, Levin and his colleagues would track hate groups and nobody would care. He's been doing this for years. Now, however, he gets calls every day, and not just from other scholars or researchers in extremism.
"That's indicative of something," Levin said. "In other words, that there is some kind of breach of the wall between extremism and mainstream politics. And I'm not saying this as someone who's a partisan. I'm saying this as someone who tracks extremist movements."
Rising misinformation and alternative information sources like Breitbart are having an impact on this phenomenon.
"In the past, conservatives would not want to fully embrace reaching out or even exploiting or spreading positions that are tied to conspiracies and overt bigotry," Levin said. “And that's not true anymore.”
The degree to which those ideologies will find their way into the White House with Bannon as Trump's chief strategist remains unclear.
"Here's the issue, and this is important,” Levin said. “We now have to determine as a nation, how much appealing to fringe aspects of politics that were previously segregated because of overt manifestations of bigotry, is going to be allowed.”
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