Demonstrators in El Paso protest President Trump’s visit to the border city Wednesday after a mass shooting on Aug. 3. (Andres Leighton/AP)

Hours after the mass shooting in El Paso last weekend, Dan Stein, president of the Federation for American Immigration Reform, issued a tweet in the organization’s name denouncing the “tragic” carnage and urging Americans to “stand together against senseless rage and destructive impulses.”

FAIR, a leading proponent of restricting immigration, typically provides its 300,000 followers on Twitter and 2.1 million on Facebook with links to studies, news stories and podcasts warning of the economic, public safety and environmental costs of high immigration levels.

But Stein made no mention in his tweet of the online document police believe was written by the alleged killer, Patrick Wood Crusius, which cited many of the same arguments against immigration as a rationale and motivation for the attack that killed 22 people in a predominantly Hispanic city near the U.S.-Mexico border.

Stein’s decision to rapidly issue a statement condemning the El Paso massacre — the group did not comment on the weekend’s other mass shooting, in Dayton, Ohio — reflects a sense of alarm among FAIR and the small cohort of other restrictionist groups about potential political fallout from the massacres.

Long relegated to the fringes of the debate, these organizations have moved center stage under President Trump — helping to provide the intellectual and ideological framework for the administration’s hard-line immigration agenda, one that immigrant rights advocates have decried as xenophobic and racist.

In an interview, Stein repeatedly brushed aside connections between FAIR’s ideology and the suspect’s, casting doubt on whether Crusius wrote the document and saying it was unfair to attribute those views as the reason for a deadly rampage.

“Any lunatic could can take paragraphs strung together from many different places and try to rationalize irrational behavior,” Stein said. He suggested that the suspect was mentally ill and criticized Democrats for trying to exploit the mass shooting for political gain.

“The fact that this alleged manifesto was picked up by people desperate for attention in the crowded Democratic [presidential] field before the blood was even cleaned off the floor tells you everything about the 2020 election,” he said.

Since the El Paso shooting, Democrats have intensified their condemnation of Trump, alleging, in the words of former vice president Joe Biden, that he had “fanned the flames of white supremacy.” In the weeks before the attack, Trump issued racist tweets suggesting that four minority Democratic congresswomen “go back” to foreign countries, even though they are Americans, and he disparaged Rep. Elijah E. Cummings (D-Md.), who is black, and criticized his district in Baltimore as a “disgusting, rat and rodent infested mess.”

Other mass shooters over the past two years have echoed some of Trump’s language about immigrants, including a gunman at a Pittsburgh synagogue last fall who decried immigrant “invaders” at a time when Trump was warning of an “invasion” of Central Americans at the border. But the online document linked to Crusius represents perhaps the most pointed connection between anti-immigration sentiment and white nationalism.

The statement attributed to Crusius mentioned a “Hispanic invasion” of Texas and expressed worries that the United States was in the process of a “cultural and ethnic replacement.” It cited fears that immigrants would swamp taxpayers with free health care and other benefits, take over jobs and intensify the strain on environmental resources.

The higher birthrate of migrants, the statement argued, would speed up the cultural change, and it emphasized that the writer’s beliefs predated Trump’s election.

FAIR, along with two other Washington-based restrictionist groups, the Center for Immigration Studies (CIS) and Numbers USA, have avoided linking their positions to race or ethnicity, but they have pushed similar arguments about the burden that immigrants place on all Americans, and the purported difficulties they pose to assimilation in American culture and society.

“If you have a guy who is going to be angry about immigration, have a killer offering reasons for shooting up immigrants, how could he not use reasons that have already been articulated by legitimate sources?” said Mark Krikorian, executive director of CIS, who called the online document “remarkably well-written for a 21-year-old loner.”

After the shooting, Krikorian wrote on Twitter that “it takes a special kind of evil to shoot children,” and said the case appeared to be politically motivated violence that was meant as a terrorist act.

“There’s only so many concerns about immigration,” he said. “Of course he’s going to articulate reasons that already have been spelled out in great detail by immigration skeptics. I don’t know how you avoid that.”

All three restrictionist groups received significant funding and foundational support from John Tanton, a Michigan doctor who professed support for eugenics, a widely debunked belief that certain beneficial human traits can be made more prominent in a population through selective breeding.

Tanton, who died last month at 85, rejected criticism that his interest in immigration was based on race and ethnicity. But according to a 2011 profile in the New York Times, he wrote to a donor that he was concerned about “the decline of folks who look like you and me,” and he warned a friend that “for European-American society and culture to persist requires a European-American majority, and a clear one at that.”

The document attributed to Crusius referred to “The Great Replacement,” a 2011 book by Renaud Camus, a French writer who promoted white-nationalist conspiracy theories that global elites were working to replace white Europeans with Muslims from Africa and the Middle East.

The Southern Poverty Law Center has included FAIR and CIS on its list of hate groups. In January, CIS filed a federal lawsuit, saying the designation had damaged the think tank’s reputation.

“There are some extreme ideologies out there, whether on the left or right, and none of them should be acceptable, and we ought to have a civil discourse,” said Ira Mehlman, a FAIR spokesman. “Our position is that everybody needs to moderate their tone.”

Asked about Trump’s tone, Mehlman struggled to find the right words before stating: “Look, he needs to recognize that his words and his tweets carry a lot of consequences and, like everybody else, should be used judiciously.”

Stein was less circumspect, saying that “people can argue that Trump’s style can be tamped down and he could be more eloquent. But nothing Trump has ever said, ever articulated, in a million years could possibly justify or be used to rationalize the behavior in El Paso.”

The three groups have small staffs but outsize influence, with top officials appearing on Fox News Channel and writing opinion pieces for conservative news outlets, including Fox News and National Review.

Top Trump administration aides, including White House adviser Stephen Miller, the man behind some of the administration’s most restrictive policies, have met with the groups and asked them to pass along studies and data.

Jon Feere, a former policy analyst at CIS, now serves as a senior adviser at Immigration and Customs Enforcement. Julie Kirchner, who worked at FAIR for a decade, is the ombudsman at U.S. Citizenship and Immigration Services (USCIS), while two other FAIR alums, Elizabeth Jacobs, a former lobbyist, and Robert Law, who was the group’s government relations director, serve as senior advisers at USCIS.

Their presence illustrates an important distinction. While the president rails most often in public about illegal immigration, the groups are focused more intently on the broader ideological project of slashing legal immigration levels, which the Trump administration has sought to do by limiting asylum seekers, refu­gee admissions and guest workers.

Feere led a study at CIS about the merits of birthright citizenship, a constitutional right that Trump has threatened to try to end through executive power. Jacobs, according to Mother Jones, advocated for ending temporary protected status for Salvadorans, reducing refu­gee numbers and defunding sanctuary cities, which are also steps Trump has pursued.

The document attributed to Crusius did not appear to distinguish between legal and illegal immigration, blaming corporations for importing low-wage and high-skilled workers and lawmakers in both parties for allowing it.

“He did not cite our work,” Krikorian said. “It had nothing to do with us.”