Political bias is a fact of life on college campuses, one that has erupted with growing fierceness in recent years.

Partisan fault-lines are sharper now too. Most conservative-leaning Americans have lost esteem for American higher education’s impact on the nation, according to a Pew survey last year—while most liberals still see them as a positive force in public life. The lefty professoriate, right-wingers tend to believe, bears outsize influence on college kids. They are correct that a leftward bias persists on campus. But they’re wrong about its source.

A new survey from Sarah Lawrence politics professor Sam Abrams of 900 administrators shows that liberals in their ranks outnumber conservatives by 12-to-1, making them “the most left-leaning group on campus.”

The ideological leanings of college professors get too much credit from conservatives for corrupting the youth on campus. “When it comes to collegiate life—living in dorms, participating in extracurricular organizations—the ever growing ranks of administrators have the biggest influence,” he wrote in a recent New York Times op-ed. The piece spurred immense and vitriolic response from readers on both sides of the debate, he told me in an interview Thursday. More than 1,000 emails poured in—some thanking him for the clarity his work provides, others excoriating him from within either partisan encampment.

The ratio of liberal-to-conservative administrators is twice the rate among the professoriate, whom Abrams previously surveyed. And six times that of incoming students, according to a separate 2016 study. The result is that, “a fairly liberal student body is being taught by a very liberal professoriate — and socialized by an incredibly liberal group of administrators.”

Through daily life at Sarah Lawrence, he had come suspect this was the case. But it’s far from the thesis he initially set out to prove. Three years ago, he thought his faculty surveys would lead to a different conclusion. Professors' progressive bias, he suspected at first, would indicate theirs was the predominant influence on students’ ideology—but the data didn’t line up with that common preconception. “I found through original polling work, it's truly not faculty,” he says. “They are liberal and obviously people like Noam Chomsky get a lot of attention, but the reality is—it's something else.”

And so, the question remained, What's going on on our campuses? Why do they seem so out of control?

“It's not presidents, it's not students, and it's not faculty,” he found. “It's this mid-tier administration, which has ballooned in the last two decades.” Particularly with student-run social hubs like fraternities waning, and colleges competing to offer the best (and most expensive) residential programming, a significant amount of students’ time during those four years falls under the purview of a growing population of administrators.

They’re a group that, as Abrams’ survey makes clear, falls far to the left of everybody else. But they also interact with students more than any other—living on campus, and overseeing what’s commonly called “student affairs.” The “college experience,” the product that students and parents shop for, does not begin and end in the classroom. But unlike professors, mid-tier administrators are less likely to craft their intellectual—or, as it happens, ideological—influence over students with careful intention.

“In the U.S., activism by student affairs professionals is already fairly embedded into higher education,” wrote Inside Higher Ed columnist Eric Stoller in a 2016 column that raised the question, on Election Day, of whether mid-tier administrations really ought to evangelize their political views. They see themselves and their jobs—or so he gathered from the comments in a Facebook group of more than 30,000 mid-tier administrators—as “fighting injustice” and therefore as inherently activistic. Crucially, the professionals who put on such an event also inform and enforce a campus’s overly broad offensive speech policy. The “Liberation Summit” Abrams describes in the opening of his op-ed is representative: An event hosted by the college’s Office of Diversity and Campus Engagement, the summit would promote “liberation spaces” for a whole host of groups marginalized by others’ privilege.

Academics tend to tackle ideas dialectically. They’re predisposed to intellectual honesty and viewpoint diversity, Abrams found. “They believe in intellectual diversity overwhelmingly and they're trying to achieve balance," he says Academics are better positioned than almost any other field to recognize the value of fruitful disagreement and to defend the scholarly environment that fosters it from the degrading effects of external bias.

Administrators, on the other hand, “they’re professional people,” Abrams says, “often with a master’s degree, but they're coming from the real world.” From the real world, "they bring real-world exposure and worldviews”—and as the data show, “those views are incredibly one-sided.”

A college campus is meant to be a sort of sanctuary for intellectual engagement: a place to reason one’s way through conflicting ideas. Campuses’ infection by fashionable ideology, while hardly a new phenomenon, erupted in recent years due to an external pressure commentators couldn’t quite pin down. It took only a few years of academic study, though, to determine the contagion.