Demonstrators protest Trump’s anti-immigration policies along Fifth Avenue during the first day of the UN General Assembly in NYC. By Kevin Hagen/Getty Images.

Next, we must take into account that no issue has come close to immigration in its power to divide Republican officeholders from the people who elect them. For some Republican voters, immigration has become issue number one in importance, but even those who put it lower on their list of priorities often have a major grudge against their elected officials on the subject. The reason is simple: politicians have broken promises and told lies about it again and again.

Some immigration hawks start the clock already back in 1965, when senators promised, incorrectly, that a major retooling of the immigration system would have only a modest impact on the number of people coming to the country. The more important juncture, though, was in 1986, when an amnesty that was supposed to legalize 2.7 million people and implement a strict protocol of enforcement instead wound up legalizing everyone but lax enforcement and an illegal influx of another 11 million people. Meanwhile, the millions who were amnestied could take advantage of family-unification provisions in order to bring over millions more—parents, spouses, children, and siblings, who in turn could do the same. The voting power of this cohort, which has generally been resistant to enforcement, is a major part of what has caused Democrats to shy away from enforcement altogether. It’s also what causes border hawks to fear that we’re one more amnesty away from losing control of the border for good.

Since 1986, no immigration hawk has believed any promises of “amnesty now, enforcement later,” and Republicans have usually talked tough on immigration on the campaign trail, whether it’s John McCain or, most notably, Marco Rubio, who won his Senate seat as a hard-liner. But that hasn’t stopped these same elected officials from reversing course once in office, either because of secret preferences for high immigration or because of non-secret closeness to party donors. Rubio took the lead in trying to sell the Gang of Eight bill in 2013—a bipartisan effort that notably included Trump whisperer Chuck Schumer—almost certainly dooming his prospects for higher office. Donald Trump’s rhetoric on the issue appealed to his voters precisely as it was offensive and unrestrained. If the people who sounded sensible were just going to reverse themselves on enforcement, then why not go with the guy who sounded crazy? Odds were better that he’d mean business.

If Trump were to pull a Rubio, therefore, or even something less dramatic, it would topple the central pillar of his candidacy. Pat Buchanan has suggested it would be as lethal to Trump as the violation in 1990 of a no-new-taxes pledge was to George H. W. Bush, and Buchanan should know, since it helped inspire him to run against Bush in the primaries of 1992. It might well be even more damaging, since Bush had at least delivered a number of legislative achievements and, for better or worse, a swiftly concluded war against Iraq. Trump, by contrast, has delivered mainly bluster. Also, tax hikes are a reversible concession, whereas citizenship is not.

This is why so many immigration wonks are monitoring the fate of legislation that was unveiled in August by Arkansas Senator Tom Cotton and Georgia Senator David Perdue. Known as the RAISE Act, it would cause immigrants to be selected in a manner similar to that employed by Canada, which grants priority to those with high skills. It would also put an end to the current policies of “chain migration,” phasing out the current preferences for adult children and siblings, thereby also forestalling complaints that the Dreamers who receive amnesty will automatically reward those who broke the law bringing them here. The idea of pairing the RAISE Act and stricter enforcement with amnesty for the 800,000 Dreamers is being floated by immigration hawks, and indications are that Breitbart and other conservative outlets would restrict themselves to grumbling about such a bargain rather than launching a full-on attack. If, on the other hand, Trump gives away his leverage for a deal that merely boosts spending on the border, he’ll trigger an outcry.

This, then, is the lay of the land on which the deplorables are standing. To be sure, at least half of them are likely to stick with Trump no matter what. To that extent, commenters like Chris Hayes are right. But the other half care a lot about immigration policy, for reasons that have little to do with racial mysticism and much to do with taming a border-control problem that has gotten worse for most of the past 40 years. If outlets like Breitbart and the Daily Caller and voices like those of Laura Ingraham and Ann Coulter and Rush Limbaugh accuse Trump of betrayal on this issue, those deplorables are likely to take their cues from them and agree. And they’re unlikely to forgive him for it, no matter how white—or, in Trump’s case, orange—he may be.