Hunched forward in his chair, his fingertips and thumbs forming a familiar diamond shape, Donald Trump seemed to anticipate the question that Axios’s Jonathan Swan was about to ask him. “On immigration, some legal scholars believe you can get rid of birthright citizenship without changing the Constitution—” Swan began, before Trump cut him off gingerly. “With an executive order,” he interjected. “Exactly,” Swan replied. “Have you thought about that?” The president didn’t miss a beat. “Yes.”

The video teaser of the interview, which will appear in Axios’s forthcoming documentary news series on HBO, erupted in the middle of a news cycle driven by Trump’s inflammatory comments regarding immigration—his decision to dispatch the military to the U.S.-Mexico border, relentless fear-mongering over a migrant caravan of Central American “invaders,” and a white-supremacist terror attack inspired by Jewish aid for refugees. Trump, who is presiding over a midterm election next week that could determine control of the House, has been betting that a hard-line message on immigration will drive G.O.P. turnout. Yet even for a party that has largely aligned itself with the president’s nationalist rhetoric, what Trump proposed was radical and largely without precedent. “It was always told to me that you needed a constitutional amendment. Guess what? You don’t,” the president continued in his conversation with Swan. “You can definitely do it with an Act of Congress. But now they’re saying I can do it just with an executive order.” His subsequent claim—that the U.S. is the only country that bestows citizenship upon anyone born within its jurisdiction—was false, but the racial anxiety he was tapping into is real. “[A] person comes in, has a baby, and the baby is essentially a citizen of the United States . . . with all of those benefits. It’s ridiculous. It’s ridiculous. And it has to end.”

The idea of revoking birthright citizenship has wended its way through Washington for years. Democrat Harry Reid, former Senate Majority Leader, proposed revoking birthright citizenship in 1993, before repeatedly apologizing for it. (“I didn’t understand the issue. I’m embarrassed that I made such a proposal,” he told the Las Vegas Review-Journal.) On the right, fear of “anchor babies” has been exploited politically by even moderates such as Jeb Bush, who invoked the issue in 2015. But Trump’s decisive claim that he could get end birthright citizenship with the stroke of a pen caused critics to drop their jaws. “He obviously cannot do that,” said House Speaker Paul Ryan, noting the intractable reality: birthright citizenship has been enshrined in the 14th Amendment for 150 years and would require no less than an act of Congress or a Supreme Court challenge to knock it down, an endeavor the vast majority of legal scholars consider impossible.

Regardless of whether it is a midterm stunt, Trump’s fever dream has very real origins in the scholarship of the Claremont Institute, a right-wing think tank based in Southern California—the front line, incidentally, of illegal border crossings. The current legal argument for revoking birthright citizenship, which had percolated on the left and right in the 90s, began gaining traction in 2006, when John C. Eastman, a Claremont Institute affiliate who is a professor at Chapman University’s Fowler School of Law, published an article for the Heritage Foundation laying out a three-point argument to challenge the authority of birthright citizenship. First, according to Eastman, at the time of the 1866 Civil Rights Act, children born to foreigners were “not entitled to claim the birthright citizenship” provided by the act. Since the Act eventually became the backbone of the 14th Amendment, therefore, the original interpretation of citizenship should take precedence. Second, he argued the reading of the 14th Amendment—that birthright citizenship can be bestowed upon anyone who is “subject to the jurisdiction” of the United States—was overbroad; in Eastman’s reading, citizenship can only be bestowed upon people with “total and exclusive allegiance” to the country. If a child’s parents had not pledged fealty to America, either by becoming full citizens or establishing permanent residence, their loyalty to the Constitution would, by all definitions, be as temporary as that of their parents. (The common legal interpretation of ”subject to the jurisdiction” is that anyone who enters the country, no matter how briefly, are subject to U.S. laws.) Finally, he wrote, the policy was a medieval remnant inconsistent with the Founding and the notion that Americans need consent to be governed: “This consent must be present, either explicitly or tacitly, not just in the formation of the government, but also in the ongoing decision whether to embrace others within the social compact of the particular people.”