“Oh boy,” Donald Trump exclaimed on the campaign trail last summer, as he hoisted a colorful poster aloft for a cheering audience in Fort Lauderdale. “You’re not going to be happy with this!” The poster showed soaring immigration numbers, highlighted in bright blood-red—a menace streaming unchecked into America.

Those numbers were cooked up at the Center for Immigration Studies, a small advocacy operation in Washington that emerged, early on in the campaign, as Trump’s go-to source for research about migrants and the dangers they pose. Trump repeatedly cited CIS studies in his TV ads and speeches, tweeted links to the group’s research, and used its data to argue that immigrants are “bringing drugs” and “bringing crime” into the United States. After he implemented his controversial Muslim ban, CIS provided Trump with much-needed political cover: Media outlets from NPR to The Washington Post quoted the center’s experts defending the policy. Most, in fact, portrayed CIS as a respectable research institute—after all, the group boasts that its board of directors includes a mix of “active and retired university professors” and “civil rights leaders.”

CIS, however, is far from a reputable scholarly organization. It’s a far-right fringe group that was founded on disturbing and discredited ideas about racial inferiority. Today, CIS churns out doctored “studies” that portray an America under siege from immigrants pouring over our borders, destroying our environment, and draining our coffers.

The group was the brainchild of John Tanton, a Michigan ophthalmologist who developed an interest in eugenics after hearing about “a local pair of sisters who have nine illegitimate children between them,” as he wrote in 1969. He believed in the debunked theories of Thomas Malthus, a nineteenth-century British cleric and scholar who warned that the world would run out of resources if the population were allowed to grow unchecked. For Tanton, “overpopulation” meant people of color. To prevent nonwhites from procreating, he endorsed birth control in the United States and sterilization efforts in Africa. And to block what he called a “Latin onslaught” of immigration that threatened to subsume Western culture, Tanton founded or funded 13 think tanks and advocacy groups—a constellation of far-right organizations that form the core of the modern movement to limit immigration into the United States.

CIS, which Tanton founded in 1985, was specifically designed to give the nativist movement a semblance of legitimacy. According to a letter buried deep in the bowels of the Bentley Historical Library in Ann Arbor, in one of 14 boxes of his correspondence open to researchers, Tanton imagined “a small think tank” that would be deployed to “wage the war of ideas.” As a serious organization with a respectable-sounding name, it would create policy briefs for conservative candidates and members of Congress—and provide cover for the lobbying efforts of its rabidly xenophobic sister organization, the Federation for American Immigration Reform, founded in 1979.

In search of funding to launch CIS, Tanton wrote to a friend, Cordelia Scaife May, the reclusive heiress to the Mellon family’s banking fortune. An environmentalist obsessed with protecting birds, May shared Tanton’s fear that immigrants would overrun America’s “native” population. During the 1980s, she became obsessed with The Camp of the Saints, a controversial French novel about “kinky-haired, swarthy-skinned, long-despised” Third World immigrants who destroy Western civilization. May paid for U.S. distribution of the novel, which depicts the mayor of New York City being forced to live in Gracie Mansion with families from Harlem.

With funding from May, Tanton founded CIS a year before Ronald Reagan signed a sweeping amnesty bill that offered nearly three million immigrants permanent legal status in the United States. The move sparked a Republican backlash against immigration, led by hard-line nativists like Pat Buchanan, and the foundations of wealthy right-wing donors—from thoroughbred breeder John Olin to garlic magnate Jaquelin Hume—began funneling millions into CIS. Although May died in 2005, her foundation, Colcom, has donated more than $76 million to block immigration reform in Congress.

CIS provided the ammunition for that fight. From a nondescript office building on K Street, its researchers churn out study after study laying out the perils of immigration. Most follow a predictable pattern: They twist the numbers to show immigrants pushing Western civilization to the brink of disaster. One 2008 report blames immigrants for America’s “burgeoning street gang problem.” Another, published two years later, argues that immigrants are using up the water in the American Southwest, making them the true threat to the environment. Yet another study, published in 2015, asserts that a whopping 51 percent of immigrant households are leeching off welfare—even though undocumented immigrants have been banned from receiving welfare since 1996. CIS’s research methodology is so flimsy that even hard-core conservative organizations have condemned it. “Simply put,” the Cato Institute wrote of the welfare report, “the CIS study does not compare apples to apples but rather apples to elephants.”

After Barack Obama took office and agreed to welcome thousands of Syrian refugees into the United States, CIS joined forces with the radical right, circulating links to white nationalist publications like VDARE and American Renaissance. The group has also embraced thinkers expelled from more polite conservative circles. Last year, CIS began publishing the works of Jason Richwine, a right-wing analyst who was forced to resign from the Heritage Foundation amid controversy over his Ph.D. dissertation, in which he suggested that there is a “genetic component” to lower IQ scores among Hispanics and other groups, and asserted that it is “difficult to argue against” the “prediction that new Hispanic immigrants will have low-IQ children and grandchildren.” Even conservatives were appalled. “Now CIS is falling down the same Alt Right pit that Tanton for years has denied courting!” the conservative news site Red State observed. CIS, it seemed, had become too radical even for the mainstream GOP.

Trump, however, has made CIS respectable. “He legitimized them in a very big way,” says Mark Potok, a senior fellow at the Southern Poverty Law Center. Thanks to Trump, the group is now routinely and respectfully cited by mainstream news outlets as a “conservative think tank,” with no mention of the kind of “alternative facts” it promotes about immigration. When the president’s advisers go on television to argue that Trump drew the largest inauguration crowd in history, or to justify new travel restrictions based on a nonexistent terrorist attack in Kentucky, it’s easy to dismiss such claims as ridiculous. But when anti-immigration screeds cooked up by CIS are presented as serious research reports, the lies are harder to spot—and play a far greater role in shaping public policy.

Editor’s Note: This article has been altered to clarify the beliefs that Jason Richwine expressed in his Ph.D. dissertation.