What is America’s immigration debate really all about? To hear Hillary Clinton and other Democrats explain it, our most urgent priority is to create a new amnesty program for millions of “undocumented” immigrants. Indeed, over the past decade, Democrats have succeeded, with the help of many Republicans, in making amnesty the focal point of “comprehensive immigration reform.”

As a result, leaders of both parties have neglected the most important question about U.S. immigration policy: How can we make the level and composition of immigration more conducive to cultural assimilation, broad-based prosperity, and public safety?

By failing to answer this question, and by impugning the motives of people who raised it, America’s political and media elites helped create the conditions in which a blustery populist could seize the GOP presidential nomination. It’s now painfully clear that Donald Trump does not actually know much about his signature issue. (Witness his confused remarks about President Obama’s deportation record at Wednesday’s debate.) Yet even if (or when) Trump loses on November 8th, the legitimate concerns expressed by his voters are not going away.

Yale professor David Gelernter put it well in a recent Wall Street Journal article:

People say [Trump] became a star because he just happened to mention an issue that just happened to catch on. But immigration is the central issue of our time. Trump voters zeroed in because they saw what most intellectuals didn’t. What is our nation and what will it be? Will America go on being America or turn into something else? That depends on who lives here — especially given our schools, which no longer condescend to teach Americanism.

The liberal theory is that, other things being equal, all human beings have an equal right to settle in America. For liberals this is too obvious to spell out. But it is also too ludicrous to defend. Does all mankind have a right to camp in your backyard, eat in your kitchen, work at your office and borrow your best jogging outfit? We fail in our duty if we don’t think carefully whom we want in this country, who would be best for America.

For those reasons, the immigration issue would not be “taken off the table” if Congress passed an amnesty bill. Leave aside the fact that a new amnesty program would encourage more illegal immigration. Even if there were not a single immigrant living here unlawfully, the level and composition of legal immigration would remain crucially important to America’s future.

Right now, most Americans oppose higher levels of immigration, and a sizable percentage — including a large majority of Republicans and Republican leaners — believe immigration should be reduced. By contrast, the bipartisan Gang of Eight bill would have massively increased immigration levels.

All of that helps explain the Trump phenomenon. It also confirms that elected officials tend to have different immigration priorities from the general public.