Two days after ISIS attacked Paris, The New York Times published a front-page story suggesting that terrorism’s new centrality to the presidential race might be “prompting voters to reconsider their flirtations with unconventional candidates and to take a more sober measure of who is prepared to serve as commander in chief.”

Nope. In poll after poll after poll since then, Donald Trump’s support has gone up. The public’s new focus on terrorism may have hurt one outsider candidate, Ben Carson, but it has helped Trump, who according to a recent ABC News/Washington Post poll, Republicans trust to handle terrorism by a 24-point margin over his nearest competitor.

This may seem crazy, but it’s not. The Republicans who support Trump—who disproportionately lack college degrees—are largely what Walter Russell Mead calls “Jacksonians.” Jacksonians—whom Mead distinguishes from democracy-spreading “Wilsonians,” commerce-oriented “Hamiltonians,” and empire-fearing “Jeffersonians”—are hawkish isolationists. Unlike GOP elites, they don’t see American hegemony as a virtue in and of itself. They don’t like spending money or sending troops abroad. They don’t see free trade, let alone mass immigration, as unambiguously good. They don’t believe that American security depends on democratizing far-off lands, something they suspect is impossible. And when there’s a crisis in some other part of the world, their first reaction is likely to be: Why can’t the countries over there handle it?

But when they are convinced America is under attack, Jacksonians become ferocious. Although slow to support America’s entrance into World War II, they overwhelmingly backed America’s decision to end it by dropping atomic bombs on Japan. They’re the kind of people who, during Vietnam, told pollsters that America should either bomb North Vietnam back to the stone age or get the hell out.

Jacksonians love leaders who mercilessly squash America’s enemies without getting too entangled overseas. One such leader was Ronald Reagan. Taking power after the humiliation of the Iran hostage crisis, Reagan convinced Jacksonians that he had restored American strength and honor by invading Grenada, bombing Libya, and rebuilding the military. But, like them, he had little patience for sending American troops into messy situations abroad. And when hundreds of American Marines died while serving as peacekeepers during Lebanon’s chaotic civil war, Reagan quickly brought the rest home.  Another Jacksonian favorite was Joseph McCarthy, who told Americans that battling the Soviet Union did not require costly foreign deployments or complex international alliances. America could keep itself safe simply by rooting out communists at home.

Trump is now a third. He’s distinguished himself from his establishment GOP rivals by opposing costly interventions in the greater Middle East. He’s said the wars in Iraq, Libya, and even Afghanistan were mistakes. He’s scorned democracy-promotion, saying he prefers dictators like Saddam Hussein and Bashar al-Assad to the chaos that follows. And when Vladimir Putin began bombing Syrian rebels last month, Trump responded, “Let Russia take care of ISIS. How many places can we be?”

Most importantly, like McCarthy, Trump has responded to Americans’ fear of foreign threats by arguing that the real menace lies within. Since the Paris attacks, while the “serious” GOP contenders have proposed establishing no-fly zones and arming Kurdish rebels in Syria, Trump has focused on registering Muslims and closing mosques in the U.S. while insisting that he “watched ... thousands” of Muslims in New Jersey celebrate 9/11. He’s turned the terrorism debate into an extension of the immigration debate that powered his candidacy this summer. And among Jacksonians, his message is resonating for the same reason McCarthy’s did: Because if the core problem is treason at home, not geopolitics abroad, then solving it is cheaper and simpler. Instead of solving the world’s pathologies, you simply expel them from your midst.

I have no idea whether Trump’s poll numbers will hold up, or whether they’ll translate into votes next year. But the idea that Republicans will abandon Trump as they grow more afraid of terrorism makes no sense. Fear of the outside world has been propelling him all along. And if there’s a significant jihadist terrorist strike in the United States between now and next spring, Trump could well propose expelling large numbers of Muslim immigrants from the country or somehow detaining them. His poll numbers, I suspect, would continue to rise.