Patrick Casey blended in easily with the buttoned-up crowd at the Conservative Political Action Conference held outside Washington, D.C., earlier this year.

His boyish face was clean-shaven. His brown hair was close-cropped. And he shuffled between the networking breakfasts and panel discussions wearing a maroon sweater, matching collared shirt and crisp khaki pants.

But despite all outward appearances, Casey, 29, wasn't like all of the other Republicans at CPAC, the largest annual gathering of conservative activists in the U.S.

He wasn't there only to champion conservative causes. Casey had ulterior motives: to covertly spread the message of the white nationalist group he leads.

As the executive director of Identity Evropa, Casey is on a bold mission. "To take over the GOP as much as possible," he told NBC News.

Casey and his roughly 800 fellow members believe ethnic diversity damages the country. Emboldened by President Donald Trump's rhetoric on race and immigration, they advocate for allowing only Caucasians to immigrate to the U.S. in order to maintain a "white supermajority."

In Casey's perfect world, whites would live among whites in North America, Western Europe, Australia, and South Africa, blacks would live among blacks in Africa, Asians in Asia, and Hispanics in Latin America. "Ethnic diversity has been proven time and time again in many studies to be very detrimental for social cohesion, social capital, and it's just not a good model for society," he said.

Identity Evropa gained notoriety last year when it helped organize the Unite the Right rally in Charlottesville, Virginia. The gathering of white supremacists ended with a white nationalist plowing his car into a group of counterprotesters, killing 32-year-old Heather Heyer.

Casey now sees politics rather than protests as the prime vehicle to carry his brand of white identity politics into the mainstream.

He knows that his extreme racial views are unwelcome in many corners of the country. So Casey takes pains to present himself as a clean-cut, upstanding young professional.

His group follows strict appearance rules: no visible tattoos, good grooming, only conservative clothing. When chatting up young people at events like CPAC, Casey knows it's crucial that he looks the part of your typical Republican booster.

"I didn't walk in there with, you know, an Identity Evropa flyer pasted on my forehead or anything," Casey said. "But I did have many great conversations with particularly the younger attendees, college Republican types."

Casey's strategy is focused on that very demographic.

He has directed his members to blanket college campuses with recruiting fliers as part of a nationwide effort spanning schools from San Diego State University to New York University. The goal: seed College Republican groups with Identity Evropa members as a stepping stone to careers into politics.

In other words, follow the path of James Allsup.

Two years ago, Allsup was the head of the College Republicans at Washington State University where he gained attention for his online rants against minorities and the "Trump Wall" he built on campus.

In June, the outspoken Identity Evropa member took a step in moving up the GOP ladder, landing a position as an elected precinct county officer in Whitman County, Washington.

The 23-year-old ran for the position unopposed, but all that matters to Casey is that he secured the GOP position at all. Though in Casey's eyes, Allsup made a crucial mistake along the way: He expressed his views too openly.

Allsup's appointment prompted strong rebukes by some local Republican leaders and led to the resignation of the Spokane County Republican Party's chairwoman after a video surfaced showing her defending him at a group meeting.

"He should not be allowed to speak to anybody that could be associated with the Republican Party," Spokane County Sheriff Ozzie Knezovich said at an August news conference, according to local NBC affiliate KHQ.

For Casey, the sharp criticism only validates his strategy.

His philosophy calls for identitarians, the term he and his ilk use to describe themselves, to infiltrate the Republican party without broadcasting their polarizing views on immigrants and nonwhites.

"Allsup is a capable and intelligent man, but ideally our members interested in getting involved in politics will do so covertly — that is, without openly identifying as identitarians, at least not upfront," Casey said.

NBC News reached out to several prominent Republican members of Congress seeking comment on Identity Evropa's statements and tactics but none responded to the requests.

A spokesman for the Republican National Committee declined to comment on Identity Evropa itself, saying he didn't want to elevate the group. Instead, he referred to a resolution that the party passed in the wake of the violence in Charlottesville.

"The racist beliefs of Nazis, the KKK, white supremacists and other like-minded groups are completely inconsistent with the Republican Party's platform that states 'all Americans stand equal before the law' and their racist agenda has no place in the United States," it said.

Patrick Casey, executive director of Identity Evropa, in an interview during the 2018 American Renaissance Conference near Nashville, Tenn. NBC News

Experts say groups like Identity Evropa represent a new wave of white supremacists who are more sophisticated and strategic than their predecessors. "These are very smart, very savvy groups and that's one of the things that differentiates them from groups of the past," said Cynthia Miller-Idriss, a professor of education and sociology at American University. "You can't just write them off as ignorant thugs."

Heidi Beirich, director of the Southern Poverty Law Center's Intelligence Report, described Identity Evropa as one of the "most active of the new hate groups" and "one of the foremost purveyors of white supremacist propaganda in the U.S."

Identity Evropa was founded by Marine veteran Nathan Damigo. Damigo was serving six years in prison for armed robbery when he joined a white supremacist gang and discovered books by a former grand wizard of the Ku Klux Klan, David Duke.

Damigo was released in 2014. Two years later, he formed the group with the help of now well-known white nationalist Richard Spencer. But Damigo stepped down in the fall of 2017 after a video surfaced online showing him punching a female Antifa protester in the face during a protest at University of California, Berkeley.

Casey took the reins in early 2018 and continued the push to infiltrate the GOP ranks in order to influence politics and culture.

The organization only accepts whites of European descent who are non-Jews. Members are banned from dating anyone outside of their race.

Casey runs Identity Evropa from a laptop in his home a few hours outside Washington. Much of the work involves posting podcasts online from members around the country, as well as disseminating photos of propaganda flyers posted to the group's 30,000-plus followers on Twitter.

Patrick Casey leading a rally at the Mexico border. Identity Evropa

Casey also leads the group in what he describes as "actions." Over the summer, Casey and two dozen of his members unfurled a giant banner on a 50-foot archway over Fort Tryon Park in upper Manhattan. "Stop the Invasion. End Immigration," it read.

In July, more than a dozen Identity Evropa members and supporters gathered outside the Mexican Consulate in New York City and held up giant green and white cut-out letters that spelled out "BUILD THE WALL."

Casey, with a megaphone in hand and a "Make America Great Again" hat on his head, marched up and down the block revving up the group of young men.

"It's predicted that by 2045 white people are going to be a minority in this country," he said. "That is unacceptable."

Then Casey led them in a chant that left no doubt where his group's political aspirations lie. "Make America great again!" they hollered.