For Ted Cruz, it’s the second issue listed on his website. It’s in Rand Paul’s top 10. Same with Huckabee. Donald Trump exploited it to instantly ascend in the polls and Scott Walker is veering sharply right to make up for loose words about citizenship. For Marco Rubio and Jeb Bush, it’s been a prominent issue they’re now burying, having offended The Base with attempts to offer reasonable solutions to a problem.

The issue is immigration, or, in GOP parlance, porous borders, lax enforcement, and a lawless president in the White House.

It is certainly one of the litmus tests of the 2016 campaign. The Republican candidates and their colleagues in Congress regard immigration reform hostilely, because it “rewards” illegality with amnesty and even citizenship; enables immigrants to steal jobs from deserving Americans; and is a political ruse to recruit new voters to the Democrats. With President Obama’s attempt to create some reform momentum by executive order, conservatives tie his “illegality” (abusing executive authority) to the “illegal” immigrants, mostly Mexicans, who number about 11 million.

The actual offense of illegal immigration is a civil infraction called “entry without inspection,” which doesn’t even rise to the level of a misdemeanor.

We will hear these talking points aplenty in the coming months. They are virtually identical to those of the 2012 and 2008 primaries, apart from the presidential candidates’ reaction to Obama’s order to not deport undocumented adults with no criminal record who are parents of one or more U.S. citizens, and not to deport youngsters brought into the country illegally as children. Even though the president’s actions are popular, as is reform to legalize and even grant a path to citizenship for unauthorized immigrants—only about a third of the public opposes such action—the Republican Base is adamant and will demand the fealty of its candidates. So far, the party’s White House aspirants are complying.

But the irony in this political quagmire is that Republicans articulate their opposition to “amnesty” in ways that have no central relevance to the immigration debate. The consistent and growing support for legalization, and even support for Obama’s executive order, means that issues like legality and job stealing no longer have traction. The jobs argument has faded as it’s become apparent how beneficial even illegal immigration is to the U.S. economy.

Why, then, the devotion to this losing issue among The Base? The fervor of the right-wing disgruntlement about immigration stems from a deeper cultural well. It’s part of a broad identity crisis that includes issues like same-sex marriage or fears of Islamic terrorism. At the extreme end of this is neo-Confederate Dylann Roof murdering black parishioners in Charleston because “you rape our women and are taking over our country” and intimidating stunts like a menacing biker brigade armed with automatic weapons outside a Phoenix mosque in early June, holding signs that read: “Stop Islam.”

Much of the opposition to immigrants (little of which is violent) is rooted in a belief that the United States is being overwhelmed by people who don’t share the values that made America great—hard work, Christian morality, patriotism, respect for law, fluency in the language of the Declaration and the Constitution. Mexicans, by contrast, remain mired in stereotypes of indolence and petty crime, with no loyalty to the United States, and a refusal to speak English and otherwise assimilate. It is a cultural clash at root, driven by a minority of American-born Anglos who see themselves as besieged by foreigners, sexual licentiousness, a terrorist threat, and the erosion of the American Way of Life. It is occasioned by 40 years of no income growth for 80 percent of American households, and the anger and frustration this spurs is expressed in cultural discontent, particularly toward the surge of Mexican immigration.

White-Hot Nativism

While working on a book, I witnessed this cultural anxiety most vividly in Arizona, where a curriculum controversy at Tucson high schools has roiled the state. More than a decade ago, educators created a Mexican-American Studies program (MAS) that mainly taught history and literature to Tucson’s large Mexican-American population. The program raised the graduation rate of these students, and their admission to college, but it included some edgy elements, including books by Paulo Freire (Pedagogy of the Oppressed) and Howard Zinn (A People’s History of the United States). This set off the Anglo power structure, particularly Arizona Superintendent of Public Instruction Tom Horne, and his successor, John Huppenthal. What ensued over several years (and remains tumultuous) was a battle over the existence of the program itself, even though it clearly had helped engage many marginalized students. Horne and Huppenthal blasted MAS as anti-American, and managed to have a law passed prohibiting such a program if it promoted ethnic division. They used that law to shutter MAS. Students organized and protested, including a sit-in at a Tucson School Board meeting. (Huppenthal was caught using fake identities to make racist remarks on social media and lost his election last year.)

Arizona, which is in a permanent broil over immigration, pits an aging white elite (many of whom have come to Arizona from elsewhere) against a growing Mexican-American population, many of whom are recent arrivals and about half of whom are there without authorization.

The culture clash goes beyond what’s taught in high schools. Maricopa County (Phoenix) Sheriff Joe Arpaio, cited numerous times for civil rights violations of immigrants, and the armed Minutemen once “guarding” the border, have been the most militant expressions of this clash. For them and many others, the issue is legality. Yet the actual offense of illegal immigration is a civil infraction called “entry without inspection,” which doesn’t even rise to the level of a misdemeanor.

In fact, legal status is a very malleable thing. Before the 1965 immigration act, Mexicans and other Latinos could enter the U.S. at will. That act, which liberalized immigration policy, was a setback for Latinos, sharply restricting the number of visas available to them. So the practice of labor migration to and from Mexico suddenly was made illicit. Yet certain legal rights are still provided to unauthorized immigrants in certain situations—protection from discrimination, for example, or allowing immigrant children to attend school. In the president’s new executive orders, good behavior is rewarded by suspending deportation.

A Sense of Belonging

Right-wing radio and TV entertainer Laura Ingraham said Hispanics are plotting to take over the Southwestern U.S.

Legality is in this way a cultural value: it conveys a sense of belonging, or admission to the club. If you’ve been here for years, been law-abiding and hard working, you have a better chance of staying. Conversely, tarring immigrants as “illegal aliens”—even if they’ve been here for decades—is a means of delegitimizing them. Something similar happened to Southern blacks, before and after they migrated north and west to escape Jim Crow. They were citizens, of course, but through discriminatory electoral laws, unequal treatment in courts, and institutional racism throughout society, they were denied the full flower of citizenship.

The most sensitive issue today, however, seems to be language. The use of Spanish in government and corporate services rankles the nativists, and, to some degree, they have public opinion on their side. Large majorities support making English the official language of the United States, though what that means as a practical matter is unclear. The lack of English language skills among Hispanic immigrants—only 23 percent speak English proficiently—gives rise to the charge that they don’t want to assimilate. But the pattern of English fluency in second and third generations follows that of other immigrant groups over many decades; even in the second generation, 88 percent of Hispanics are fluent in English, according to the Pew Research Center.

Despite this ready assimilation, some nativists see Mexicans clinging to their own culture—language, rituals, holy days, food, sports—as evidence of a not-so-secret desire to transform America. Right-wing radio and TV entertainer Laura Ingraham said Hispanics refuse to learn English because they’re plotting to take over the Southwestern U.S. Others in the right-wing blogosphere make similar claims, including ominous warnings about the danger of criminal infiltration (terrorists, rapists, and drug dealers mainly). Notably, the crime rate among immigrants of all kinds is one-quarter that of native-born Americans, but the criminal class meme remains strong.

Republicans and Democrats alike emphasize border security, but spending more than the $18 billion allocated yearly will matter little to desperate immigrants. What’s needed to prevent more people coming is sustainable economic development in Mexico and Central America. Meanwhile, the ferocious hostility toward Hispanic immigrants by conservative activists is gumming up Capitol Hill so much that reform is nearly unimaginable.

The cultural roots of anti-immigration reform will be hard to eradicate. Looking beyond 2016, the next president should confront the cultural anxiety about work ethic, patriotism, language, legality, and crime. At times of economic and security stress, this anxiety has appeared often in U.S. history, previously aimed at Italians or Poles or Chinese, among others. The Republic has survived, and its core values remained undiminished. That’s likely to happen—is happening—with Hispanics, who, like immigrants of all nationalities, are fervent believers in the American Dream.

John Tirman is executive director of the MIT Center for International Studies, and author of Dream Chasers: Immigration and the American Backlash.

This article will appear in the September 2015 issue of The Washington Spectator.