In 2016, during the waning days of Barack Obama’s two terms in office and with the imminent prospect of Hillary Clinton’s election, President George W. Bush was overheard telling a gathering of aides, “I’m worried that I will be the last Republican president.” Bush was mistaken, of course: Donald Trump eked out a narrow Electoral College victory despite losing the popular-vote tally by almost 3 million votes. But while Bush’s speculation proved to be literally wrong, it may well have been figuratively true. Donald Trump has gone on to remake the contemporary Republican Party in his own image, jettisoning the GOP’s postwar commitment to a form of conservative internationalism that was the hallmark of the presidencies of Eisenhower, Nixon, Reagan, and both Bushes.

The conservative internationalist persuasion of those Republican administrations combined the notions of peace through strength, robust support for America’s globe-girdling system of alliances and military bases, and general support for liberalizing international trade relations. Although it is still possible to find that conservative internationalism in the views of Nikki Haley and Chris Christie, the party’s center of gravity has clearly moved in the direction of the reborn “America First” mantra of Trump and his key supporters in the congressional Republican Party, including but not limited to Representatives Jim Jordan and Marjorie Taylor Greene and Senators J.D. Vance and Josh Hawley.

Those of us who worked with Bush 43 would hear him say, on more than one occasion, “One doesn’t have to scratch too deep in the Republican Party to hit a deep vein of isolationism, protectionism, and xenophobia, and it is my job as party leader to lean against and moderate that tendency.” Within that vein, there flows a latent but powerful current of antisemitism. It’s vital for conservatives, particularly Jewish ones, to understand how the Republican Party’s turn toward its old isolationist instincts under Trump poses risks to the safety of Jews in Israel and the United States alike.

For most of its first century of existence, the Republican Party had been committed to the protection of American manufacturers (in keeping with its roots in the antebellum Whig Party), wary of foreign entanglements (although Teddy Roosevelt was something of a counter-example), and blemished by its hostility to immigration, particularly of Roman Catholics.

The reluctance to become embroiled in the affairs of other countries was rooted not only in the party’s Whiggish political roots but even more deeply in the nation’s early political traditions. “The great rule of conduct for us, in regard to foreign Nations, is, in extending our commercial relations, to have with them as little political connection as possible,” said George Washington in his Farewell Address. Thomas Jefferson reflected a similar sentiment in his first Inaugural Address: “Peace, commerce, and honest friendship with all nations, entangling alliances with none.”

Staying aloof from world affairs in the 19th century — a century marked by the globalization of trade, the emergence of steam-powered, iron-clad navies, and a communications revolution powered by transoceanic telegraphic cables — was always going to be difficult. The challenge became that much more vexing in the 20th century. German U-boat attacks on shipping helped draw America into World War I, with its promise of being a “war to end all wars.” But the failure of the peace conference at Versailles to make good on Woodrow Wilson’s promise to have a peace without victors or indemnities led to profound public disenchantment, fed by the notion that the war had been waged not for grandiose ideals but to benefit Wall Street financiers and militarily connected industries.

As the peace of Europe broke down in the 1930s, Franklin Roosevelt’s attempts to work around the legal impediments that the isolationists had created kicked off a furious debate marked by what historian Arthur Schlesinger Jr. called “the searing personal impact of those angry days.” Isolationists led by Charles Lindbergh organized an America First movement to oppose U.S. involvement in the European crisis. It held tremendous appeal, particularly among elite university students: Kingman Brewster, the future president of Yale, was a member, as were future Supreme Court justice Potter Stewart, future president Gerald Ford, and Sargent Shriver, who later founded the Peace Corps.

Many of these members were youthful idealists wary of another world war. But it’s impossible to understand America First without also discussing its antisemitism. Much of it was driven by supporters of Father Charles Coughlin, a radio priest who was a New Deal opponent and a rank antisemite. The head of the Florida chapter of America First claimed that Jews “are primarily responsible for our being advanced so far along the path to war.” In September 1941, Lindbergh gave a speech suggesting that Jewish groups were playing a major role in dragging the United States into the European conflict.

The Japanese attack on Pearl Harbor destroyed the reputations and political careers of many America Firsters. Others, notably Senator Arthur Vandenberg of Michigan, recognized that the isolationism they had espoused was wrong-headed and no longer tenable in a world increasingly marked by the rise of transoceanic navies, air power, and nuclear weapons. Dwight Eisenhower’s nomination victory over Ohio’s Senator Robert Taft, the party’s leading isolationist, marked a definitive GOP turn to the conservative internationalism that largely defined it for the next 65 years.

But if conservative isolationism faded, it never went away. It was represented by Senator John Bricker of Ohio in the 1950s, and in more recent years by Republicans such as presidential candidate Pat Buchanan, Representative Ron Paul of Texas, and his son, Senator Rand Paul of Kentucky.

When Donald Trump became a serious presidential candidate in 2015, he was not particularly well-informed about foreign affairs. (Unlike most of the other candidates, he lacked even an informal group of national-security advisers and notoriously told Chuck Todd of Meet the Press, “Well, I watch the shows.”)

But Trump’s ignorance did not mean that he lacked consistent views or a fundamental outlook. He had for years decried U.S. trade policy and advocated protectionism for American manufacturers and had consistently derided America’s allies for being “free riders” who enjoyed protection from foreign threats at America’s expense. He also seemed diffident, at best, when it came to the promotion of human rights or democracy and seemed especially attracted to political strongmen.

Perhaps the first observer to spot the similarities between Trump’s views and Robert Taft’s was the Brookings Institution’s Thomas Wright, now on President Biden’s National Security Council staff. In a prescient Politico essay, Wright wrote that the New York tycoon had a “worldview that makes a great leap backward in history, embracing antiquated notions of power that haven’t been prevalent since prior to World War II.” Trump openly embraced America First as a slogan; Wright called out the echoes of not only Taft but also Lindbergh in Trump’s foreign-policy opinions dating back to the mid-1980s.

What has changed since Trump’s surprising rise to power is that the Republican Party in the electorate (and, more slowly, the Republican Party in the Congress) has shaped itself around his views despite efforts by some of the so-called adults in the room who served in his administration to smooth the rough edges off his isolationism by declaring “America First but not alone.” Hostility to lowering trade barriers, reluctance to provide additional aid to Ukraine, skepticism about America’s allies, indifference or hostility to the promotion of democracy — all this has become mainstream among Republicans. One of the most important policy consequences of this turn to isolationism is the disdainful attitude of leading Trumpists in the party toward support for Ukraine. As a Senate candidate in 2022, J.D. Vance said, “I’ve got to be honest with you, I don’t really care what happens to Ukraine one way or another.” As George Will has pointed out, Vance’s defeatism and worries about the costs of supporting Ukraine carried distinct echoes of Taft’s pre–World War II view that any aid the U.S. gave to Britain would be wasted and lost to an inevitable German victory.

The normalization of an isolationist strain that had long lain dormant in the party has been, unsurprisingly given the history of America First, accompanied by the normalization of antisemitism.

Trump has dined at Mar-a-Lago with Holocaust denier Nick Fuentes, who has also organized an America First political action committee and told conspiracy monger Alex Jones that “Jews have no place in Western Civilization because they are not Christian.” Marjorie Taylor Greene has spoken at Fuentes’s America First Conference and suggested that wildfires in California were caused by space lasers funded by the Rothschilds. Tucker Carlson, a key media voice of Trumpism, decried conservative editor and talk-show host Ben Shapiro’s support for Israel after the October 7 attacks, resurrecting the dual-loyalty trope by accusing him and others of being “focused on a conflict in a foreign country as their own country becomes dangerously unstable.”

Trump has also sought to distract from his association with well-known antisemites by pointing to his many ties to prominent Jews, including his attorneys and, of course, the conversion of his daughter Ivanka to Judaism in order to marry her husband, Jared Kushner. Trump supporters also point to his undoubted accomplishment in presiding over the negotiation of the Abraham Accords, which marked the normalization of relations between Israel and the United Arab Emirates, Bahrain, Morocco, and Sudan.

But the larger question remains of whether or not the isolationist America First tendencies that Trump has expressed, and that are now increasingly powerful in the Republican Party, threaten American support for Israel in the long run. American foreign policy is frequently depicted as either the pursuit of ideals or interests, as if that were a binary choice. In fact, both have always played a role going back to the founding of the country. And common values of freedom, democracy, and respect for the rule of law and human rights have underpinned the U.S.–Israel relationship since the latter’s founding in 1948. Devaluing those elements will corrode the relationship over the long run.

America and Israel have had a strong security relationship since the 1960s, and Israel now receives from the United States both long-term security assistance and emergency military aid since the beginning of the war in Gaza. Questioning American alliances and depicting them as purely economic transactions — or, more crudely, as protection rackets — will inevitably bleed over into discussions of the U.S.-Israel relationship. As the America First faction grows in power inside the Republican Party, the antisemitism that accompanies it will begin to undermine support for Israel over the long haul.

The liberal, rules-based international order is an abstraction that frequently obscures more than it illuminates. At its core, it consists of the system of military and political alliances and an economic order that sought to lower tariff barriers to global growth. It was premised on what seemed self-evident in the immediate aftermath of titanic and destructive conflict: that the U.S. could not stand aloof from the rest of the world and that the balance of power in Europe, East Asia, and the Middle East were interconnected and of fundamental importance to the peace and prosperity of Americans.

That order is now under attack from within and without: first, from authoritarian aggressors such as Russia, China, North Korea, and Iran, which seek to revise global arrangements to make the world safe for autocracy and theocracy; second, from illiberal democrats and populist nationalists within, who seek to make the world safe for autarchy and autochthony.

In the U.S., that populist nationalism has drawn on a long-quiescent tradition that has been reawakened and reinvigorated by Trumpism. A recrudescent America First policy will undermine American alliances and likely promote nuclear proliferation as nations pursue “sauve qui peut” policies. It will allow long-suppressed conflicts, previously tamped down by U.S. security guarantees, to resume and reemerge as security competitions. It will contribute to the global “democratic recession” by diminishing support for the rule of law and human rights. And it will undermine a key pillar of the postwar order — American global leadership and its ability to provide a framework for collective action among nations. The consequences could be disastrous in the short run for Ukraine and in the longer run for Israel, and down the road for Taiwan. It would lead inevitably to a progressively more disordered and dangerous world.

What is to be done?

First, if Donald Trump emerges as the Republican nominee, it is imperative that he meet defeat at the polls. Whatever criticisms one has of President Biden and his policies, his reelection would not present the kind of challenge that a victorious Trumpism would to both U.S. democracy and support for America’s most important comparative strategic advantage — its system of alliances.

It will also be crucial to support, in primaries as well as general elections, Republicans and Democrats who demonstrate a commitment to the system of alliances and the trade order that have undergirded the international system since 1945. That commitment, given the challenges we face in Europe, the Middle East, and East Asia, will also require continued investment in national defense that will enable the U.S. to play its role as “the arsenal of democracy” that both Roosevelt and Biden have championed.

Defeating the America First challenge will also require a fundamental reassertion by Democrats and Republicans that American values, and particularly support for democracy, the rule of law, and fundamental human rights, are central to our foreign policy. It is within the framework of those values that the U.S.-Israel alliance can best be defended and sustained. America supports Israel neither out of charity nor because of Jewish influence in American politics. Rather, we do so for the same reason America should support the security of all free nations — both as a good in itself, and because doing so is the strongest and surest guarantee of our own freedom, security, and continued prosperity.

My generation of conservatives knows these things — or used to. The time is getting late to make sure younger conservatives learn this history, too, lest they repeat it with the same tragic consequences.