Two months ago, in the first speech of his Presidential campaign, Donald Trump departed from his prepared text in order to speak—vehemently and apparently extemporaneously—about the issues that concerned him most. One of the first was immigration, and he suggested, somewhat paradoxically, that unauthorized immigrants from Mexico were out-competing American workers (“They are beating us, economically”) and also undermining American society. “When Mexico sends its people, they’re not sending their best,” he said. “They’re sending people that have lots of problems,” he added, and then he provided a taxonomy: “They’re bringing drugs, they’re bringing crime, they’re rapists—and some, I assume, are good people.”

Some observers thought that the speech was a political disaster, especially because of that one extraordinarily inflammatory word: “rapists.” But it’s clear, in retrospect, that this speech marked the beginning of the Trump surge. The speech inspired weeks of coverage, making Trump—who was unapologetic—the biggest story in political media. A few weeks after the speech, NBC announced that, “due to the recent derogatory statements by Donald Trump regarding immigrants,” it would no longer broadcast his Miss U.S.A. or Miss Universe pageants, and he would no longer appear on “The Apprentice,” the long-running reality show. It is possible that, by disrupting Trump’s television career, NBC only made him more motivated to succeed in politics. Less than a month after his launch speech, a poll put Trump, for the first time, atop the Republican heap. It is likely that, by using the R-word, Trump helped establish himself as the only Republican candidate eager to speak his mind on an issue that most of the field would prefer to avoid: immigration.

This past weekend, Trump released his first detailed policy statement, on the topic that made him a front-runner; it is called “Immigration Reform that Will Make America Great Again.” He called for more immigration officers, tougher penalties for visitors who overstay their visas, a “pause” in the issuing of new green cards, the end of “birthright citizenship,” and the construction of a “permanent border wall”—to be paid for, he said, by Mexico. This last proposal drew plenty of scorn, since it is hard to imagine how the Mexican government might be induced to spend billions of dollars on a barrier at the behest of U.S. politicians. (Trump suggested that, in the face of Mexican recalcitrance, the U.S. could “impound” remittances from unauthorized workers and charge higher fees to visitors from Mexico.) But some Trump skeptics seemed pleasantly surprised. The editors of National Review, who had previously accused Trump of “intellectual failure” for his unclear statements on immigration, offered qualified praise for the new plan. “It is sensible in its basic outline,” they wrote, “and better in many respects than the ideas presented by his rivals.”

On Tuesday night, during an interview with Bill O'Reilly on Fox News, Trump reiterated his call for “a big, beautiful, powerful wall” to be built on the border with Mexico. On the matter of birthright citizenship, O'Reilly said that Trump's plan to abolish it would be foiled by the Fourteenth Amendment, which says, “All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States.” Trump, needless to say, was unperturbed. “Many lawyers are saying that's not the way it is,” he replied—referring, perhaps, to advocates and scholars who argue that the Fourteenth Amendment has been widely misinterpreted.

Earlier this summer, it seemed that Trump’s presence in the race could actually make it easier for the other Republican candidates to avoid talking about immigration. They could merely affirm that Trump’s comments about “rapists” were “extraordinarily ugly” or “offensive and inaccurate,” repudiating him without making any specific commitments of their own. Trump’s new proposal may compel them to have the kind of policy discussion that Presidential campaigns are, in general, designed to avoid.

In early June, Pew published a new poll chronicling the country’s mixed feelings about immigration. Among other things, the poll provided yet more proof that, when it comes to immigration, Republican politicians are often out of step with Republican voters. When asked to choose between two assertions about the impact of immigration on the U.S., sixty-three per cent of Republicans agreed that immigrants “burden” the country by taking jobs, housing, and health care; only twenty-seven per cent agreed that they “strengthen” the country “through hard work & talents.” But the Republican majority was in the national minority: over all, respondents chose “strengthen” over “burden,” by a margin of fifty-one to forty-one. The numbers explain why, especially in general elections, Republican candidates like Mitt Romney and John McCain have taken pains to emphasize America’s hospitability to immigrants. But the numbers also help account for the frustration among Republican voters who have noticed that, when it comes to immigration, their own party is ignoring them.

At the same time, the Pew poll captured a broader ambivalence about immigration. Although Democrats said that they wanted unauthorized immigrants to be able to remain in the country, only forty-eight per cent said that they should be able to apply for citizenship; only twenty-four per cent said that legal immigration should be increased. Meanwhile, a majority of Republicans agreed that granting legal status to unauthorized immigrants was “like a reward for doing something wrong”—and yet a majority of Republicans, even conservative Republicans, said that unauthorized immigrants should nevertheless be “allowed to stay legally.”

It is hard to have a consistent position on U.S. immigration laws, partly because the laws themselves seem so inconsistent, and inconsistently enforced: an immigrant who evades armed guards at the border might subsequently arrive in a so-called sanctuary city, in which the federal statutes seem not to apply. Immigrants rearranging—and sometimes risking—their lives must take into account not only the laws that currently exist but also the ways in which those laws will or will not change in coming decades. One of Trump’s simplest and boldest ideas is to end birthright citizenship, the constitutional doctrine under which anyone born inside the U.S. is considered a citizen of it. (Immigration-restriction advocates argue that birthright citizenship incentivizes unauthorized immigration.) Automatic birthright citizenship is widespread in the Americas, but not beyond them; European and Asian countries have more restrictive rules. In other words, birthright citizenship is both an American tradition and a global anomaly, which means that ending it could seem either radical or common-sensical, depending on one’s perspective and objectives.

Already, Trump’s call for an end to birthright citizenship has brought some clarity to the Republican conversation on immigration. Scott Walker, who used to support a comprehensive reform that would allow unauthorized immigrants to remain in the country, told Fox News in March, “My view has changed.” In an interview with Breitbart last week, he talked about the need to “secure the border,” but offered few details. It wasn’t until earlier this week, when a reporter asked him about Trump’s proposal, that Walker seemed to say, apparently for the first time, that the U.S. should “absolutely” end birthright citizenship. Meanwhile, Marco Rubio said he was “open to doing things that prevent people who deliberately come to the U.S. for the purposes of taking advantage” of birthright citizenship, but said that Trump’s proposal to eliminate the doctrine was “really not a workable plan.” And Jeb Bush said, “We ought to fix the problem, rather than take away rights that are constitutionally endowed."

For a time, it seemed that Trump’s campaign might be merely a spectacle, albeit a captivating one. But with the release of his plan, he seems to have started something even more engrossing: a substantive political debate. After offering qualified praise for Trump’s proposal, the National Review editorial concluded on a note of skepticism: “Immigration is too important to be left to The Donald.” But perhaps the topic was too politically risky to be broached by anyone else.