(Mark Giaimo/For The Washington Post)

William H. Frey, a senior fellow at the Brookings Institution and a population studies professor at the University of Michigan, is the author of “Diversity Explosion: How New Racial Demographics Are Remaking America.”

He may not have a shot at becoming president, but Donald Trump has already succeeded in uniting America — one nation, awash in snark. Pundits from the left and the right have declared open season on the Donald. As longtime Democratic strategist Paul Begala told The Washington Post, “I am a person of faith — and the Donald’s entry into this race can only be attributed to the fact that the good Lord is a Democrat with a sense of humor.” Or, as conservative columnist Charles Krauthammer said on Fox News: “This is the strongest field of Republican candidates in 35 years. You could pick a dozen of them at random and have the strongest Cabinet America’s had in our lifetime, and instead all of our time is spent discussing this rodeo clown.”

But writing Trump off is dangerous. The billionaire may play the buffoon, but he is an important one — one whom Americans appear to adore. A USA Today-Suffolk University poll released Tuesday shows him leading all Republican presidential hopefuls. And while establishment candidates in both parties might want to ignore him, or express a milder version of his anti-immigration opinions, an enormous number of voters clearly like his views. Pretending they don’t allows Trump and other immigration firebrands, such as Rick Santorum and Ted Cruz, to resuscitate a century-old nativism that could stick around beyond this election. Given that the United States is undergoing a demographic diversity explosion, our workforce — our very future — is tied to people Trump is rallying support against.

Trump’s message is a call to 1950s American greatness and a simmering, mad-as-hell populism that blames Chinese imports, freeloading Saudis and Mexican immigrants (and Mexico) for the nation’s ills. It appeals to a vein of the U.S. electorate that will remain a significant voting bloc for several election cycles to come: older whites. Trump calls his supporters the “silent majority,” the same name Richard Nixon used to marshal support from a white, middle-class, middle-aged population that felt underappreciated and feared the dramatic social change wrought by activist, antiwar youths and the civil rights movement.

Public opinion polls and recent election results reflect similar views among older whites today. Pew Research Center data from 2012 showed that more than half of white baby boomers and seniors believed that increasing numbers of newcomers from other countries represented a threat to traditional American values. They were less likely than minorities and younger whites to hold a positive opinion of the growing numbers of Hispanics and Asians in the United States. These views translate into negative attitudes toward government programs they see as not benefitting their own children and grandchildren. A 2013 Pew survey showed that, given the choice between a larger government that offered more services and a smaller government that offered fewer, less than a quarter of white baby boomers favored larger government, compared with 7 in 10 minorities of the Gen X and millennial generations.

It is fitting that Arizona was the site of Trump’s biggest splash so far. Last weekend, he held court there with an enthusiastic throng of mostly older supporters after an introduction by Maricopa County Sheriff Joe Arpaio, a renowed immigration hard-liner. Arizona leads the nation in an emerging generation gap that reflects both culture and race. Because of its continued draw of mostly white seniors from other parts of the country and its sharp gain in youthful immigrants and U.S.-born minorities over the past 20 years, the state’s over-65 population is far whiter than its child population (82 percent vs. 41 percent white). It has, in many ways, become ground zero for the politics of fear, famous for tamping down ethnic studies in public schools and passing strict immigration measures, such as the law that requires police to ascertain immigration status when they have “reasonable suspicion” that a person is in the country illegally. (When the bill was proposed, it was favored by 65 percent of whites but only 21 percent of Hispanics; 62 percent of those ages 55 and over but only 45 percent of those under age 35.)

As minorities grow as a share of the U.S. population — they are expected to represent more than half of Americans by 2044 — so will the potential for the politics of fear. Most of the states that have sued the president over his recent executive order offering protections to some undocumented immigrants are those with relatively small but climbing immigrant populations, such as Nebraska and West Virginia.

Democrats cannot make the politics of fear go away simply by courting the young-adult and minority voting blocs. While it is true that the supersize turnout and support of those groups helped elect President Obama twice, the white portion of the electorate, which votes strongly Republican, underperformed in support of John McCain in 2008, and white turnout was down in 2012. Rhetoric playing to the fears of older Americans could change that pattern and draw more white voters to the polls in 2016.

While racial minorities now account for 95 percent of U.S. population growth and represent 38 percent of the population, as reported by the Census Bureau last month, there is a sharp lag in diversity between the overall population and the portion that turns out on Election Day. A disproportionate number of Hispanics and Asians are either too young to vote, are not citizens or are not registered, qualities that will not change for several more election cycles. Even in 2012, with strong minority turnout, whites made up 74 percent of all voters. And within the white voting bloc, it is the older electorate — those most greatly fearing change — that will be gaining as baby boomers continue to age. By my calculation, the number of (mostly white) eligible voters over age 45 will be 26 percent larger in 2024 than those under age 45. This disparity will be further widened by the higher turnout of older white voters, who may not determine future elections but will continue to have a strong voice.

Republicans especially need to stop laughing. Their upcoming debates should challenge, not ignore, the unfocused fears of immigration and national diversity raised by Trump and like-minded candidates, and instead present a more nuanced and realistic view of the future, in which the national economy will depend on investment in today’s children and racial minorities. While they are not yet the force on Election Day that they will be in the foreseeable future, racial minorities will represent all of the growth in our labor force for the next 20 years, and their success will translate into economic prosperity and future contributions to Social Security and Medicare. Trump happily appeals to older, more conservative white baby boomers and seniors, but he could do them a favor by showing them the role that our diverse younger generations — many with immigrant roots — will play in our future. Vilifying them cannot be a lasting political strategy for tomorrow. And it cannot be a working national philosophy today.

outlook@washpost.com

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A new Washington Post-ABC News poll shows businessman and 2016 presidential candidate Donald Trump leading the GOP field for Republican voters. (The Washington Post)