It’s hard to think of two American presidents with less in common than Calvin Coolidge and Donald Trump. For one thing, Coolidge held a variety of public offices, from Massachusetts governor to vice president, before assuming office on Aug. 2, 1923. Mr. Trump had no government or military experience before his inauguration in 2017.

Coolidge, moreover, was a budget hawk who never met a line item he didn’t want to cut. Mr. Trump presided over record peacetime deficits even before federal spending took a quantum leap during the coronavirus pandemic. Coolidge was also a man of few words. Trump is not.

Yet these personal differences obscure important political similarities. Both Coolidge and Mr. Trump staked their presidencies on voter satisfaction with broadly shared prosperity. Both supported restricting immigration into the United States. Both wanted to protect American industry from foreign competition. Both sought to avoid overseas entanglements.

Mr. Trump’s views now dominate the Republican Party. For anyone who grew up with the GOP of Ronald Reagan, the two Bushes and John McCain, this can be strange and bewildering. But in many respects, it’s a return to the principles of the 1920s, of Coolidge and his predecessor Warren Harding. Their conservatism was delegitimized by the crises of the 20th century. The Great Depression robbed the right of its claim to promoting prosperity. FDR’s New Deal created a federal government that Republicans did not comprehend or control. Then World War II discredited the right’s noninterventionist foreign policy. What emerged from the rubble was a postwar conservative movement that embraced alliances, military intervention, forward defense, free trade and open immigration to defeat communism and fuel economic growth.

President Ronald Reagan, here at the Berlin Wall in June 1987, embodied a more assertive GOP foreign policy.

Photo: Dieter Klar/picture alliance/Getty Images

This postwar conservative internationalism—known to its critics on the right as “globalism”—may have been an aberration. Today, the GOP is reverting to its pre-World War II identity as the party of low taxes, economic protection, restricted immigration, wariness of foreign intervention and religious piety. This retro-Republicanism could turn out to be a popular mix, but history shows that it is also a combustible one.

By the beginning of the 1920s, the American electorate had soured on its experiences with the Progressive movement and the Great War. The influenza pandemic of 1918-20, the Red-hunting of Wilson administration officials A. Mitchell Palmer and J. Edgar Hoover, and postwar recession all contributed to civil unrest. Change came in the form of a garrulous Republican politician from Ohio named Warren Harding.

“Our supreme task,” President Harding said in his inaugural address, “is the resumption of our onward, normal way.” Harding promised to reduce social tensions. He disavowed foreign intervention and withdrew U.S. occupation forces from postwar Germany. His secretary of state pursued disarmament treaties with the great powers. He opposed Wilson’s League of Nations.

For Harding, “normalcy” meant nation-building at home. He raised tariffs and restricted imports. And he venerated the Constitution. In a speech delivered in 1920, he called the document “the very base of all Americanism, the ‘Ark of the Covenant’ of American liberty, the very temple of equal rights.”

When Harding died in office in 1923, Calvin Coolidge did not depart from this constitutionalist path. To Coolidge, the Declaration of Independence and the Constitution offered the last words in a centuries-long argument over popular sovereignty. “If all men are created equal, that is final,” he said. “If they are endowed with inalienable rights, that is final. If governments derive their just powers from the consent of the governed, that is final. No advance, no progress can be made beyond these propositions.”

Republican presidential nominee Warren Harding (left) and vice-presidential nominee Calvin Coolidge during the 1920 campaign.

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Coolidge argued that success in self-government was related to religious faith. Political freedom depended on traditional morality and self-control. He called on Americans to preserve the inheritance of the Founders, to follow “the spiritual and moral leadership which they showed.”

Coolidge opposed immigration. He and Harding signed into law two restriction acts that shut off entry to the U.S. for the next 40 years. As he closed the door to mass migration, however, Coolidge also celebrated the contributions of earlier waves of immigrants. “Whether one traces his Americanism back three centuries to the Mayflower, or three years [to] steerage,” he told the American Legion in 1925, “is not half so important as whether his Americanism of today is real and genuine. No matter by what various crafts we came here, we are all now in the same boat.” But there was no room for additional passengers.

Coolidge was out of office for less than a year when the stock market crash of 1929 and the onset of the Great Depression upended the established order. His Republican successor as president, former secretary of commerce Herbert Hoover, struggled to contain the economic fallout and social disorder. “This election is not a mere shift from the ins to the outs,” Hoover said in the run-up to the 1932 election. “It means deciding the direction our Nation will take over a century to come.”

The nation opted for New York governor Franklin D. Roosevelt, whose New Deal created a bureaucratic structure of government, centralized in the nation’s capital, which quickly won the enmity of conservatives. The upheaval of the 1930s drove the partisans of strict constitutionalism and nonintervention in economics and foreign affairs from positions of power and influence.

Conservatives attacked New Deal programs like the Works Progress Administration, which employed the workers widening a street in this 1935 photo.

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The GOP was a leaderless rump until the election of 1938, when it found a new spokesman in Ohio senator Robert A. Taft. As the son of President

William Howard Taft, he had been raised to uphold the constitutionalist, free-market, noninterventionist traditions of his party. The reach of state power under FDR and its concentration in the executive branch reminded him of the new authoritarian governments in Europe. The New Deal, he said, was “absolutely contrary to the whole American theory on which this country was founded.”

Taft’s philosophy contained all the principles of his father, Harding and Coolidge. As he put it in 1938, “The regulation of wages, hours, and prices and practices in every industry is something which is, in effect, socialism; which is government regulation of the worst sort; which means a totalitarian state.”

For Taft, Roosevelt’s preparations for war against Germany were the foreign-policy equivalent of the New Deal. He had worked for Herbert Hoover at the American Relief Administration during the final years of the Wilson presidency, and what he saw amid the rubble of the Great War confirmed his loathing of great-power competition. Europe was a charnel house of nationalism, dynastic politics and class struggle. Taft wanted the U.S. to avoid it and warned against mobilizing American armed forces too quickly. “Our armament program should be based on defending the United States and not defending democracy throughout the world,” he said in response to Roosevelt’s 1939 State of the Union address, in which the president warned of the rise of Nazism and called for increased defense spending.

“In the 1920s, the right was in charge. It was self-confident and prosperous. It saw itself as defending core American institutions.”

In the view of Taft and other noninterventionist conservatives, war would expand government, lead to rationing, and invest FDR with a dangerous amount of authority. The U.S. should defend the mainland and the Caribbean basin, Taft said, but otherwise it should leave the conflagration in Europe to burn itself out. His priority was the home front. “There is a good deal more danger of the infiltration of totalitarian ideas from the New Deal circle in Washington,” he told a St. Louis audience on May 20, 1940, “than there will ever be from any activities of the communists or the Nazi bund.”

Taft neither joined nor spoke for the antiwar America First Committee, but he welcomed its appearance on the national stage. The organization was established in 1940 in Chicago. Its founders included graduates of some of the nation’s elite educational institutions, and it drew support from Republicans, Democrats, Progressives, conservatives and even figures within the Roosevelt administration.

Former president Hoover belonged to America First. One of the chief organizers was a Yale Law student named Gerald R. Ford. A Harvard undergraduate named John F. Kennedy contributed a $100 check. The Buckleys, a wealthy oil family living in Sharon, Conn., named one of their sailboats Sweet Isolation.

America First wanted four things. First was an “impregnable” national defense. Second was preparedness to thwart an attack on the American homeland. Third was neutrality in the ongoing war in Europe—which meant, in effect, leaving the U.K. as the last line of defense against Nazi conquest. Fourth was resistance to providing the British “aid short of war.” The committee’s demands resembled Taft’s. But it also had something that eluded him: widespread appeal.

A 1940 poster from the America First Committee opposing U.S. involvement in World War II.

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Taft was cold, cerebral, withdrawn. “I’m afraid you won’t find much color in me,” he once told a reporter. “I’m too damned normal.” By contrast, America First’s spokesman, Charles Lindbergh, was an aspirational figure whose triumphal (and, after the murder of his child, tragic) story commanded respect.

Lindbergh was an icon to noninterventionists, especially in the Midwest, but a villain elsewhere. His refusal to condemn the moral depravity of the Nazis polarized audiences. He rubbed shoulders with fascist sympathizers and anti-Semites. America First could not escape the stench of Nazism. The committee spent much of its time distancing itself from pro-Nazi groups and figures.

Lindbergh drew a moral equivalence between the governments of the U.K. and Nazi Germany. He singled out for blame scapegoats who he said agitated for American intervention. He became the symbol of an unfeeling and sinister isolationism. Proud of his service in the U.S. Army, he resigned his commission after Roosevelt likened him to a pro-Confederate copperhead Democrat.

Lindbergh’s infamous speech in Des Moines, Iowa, on Sept. 11, 1941, marginalized the antiwar cause and associated it with anti-Semitism. Lindbergh singled out “the British, the Jewish, and the Roosevelt administration” as the three groups “who have been pressing this country toward war.” His wife urged him to include a statement of opposition to anti-Semitism. He refused. “I am saying,” he told the cheering crowd, “that the leaders of both the British and Jewish races, for reasons which are understandable from their viewpoint as they are inadvisable from ours, for reasons which are not American, wish to involve us in the war.” By defining Jews as “not American,” Lindbergh effaced more than a century of American religious toleration.

Charles Lindbergh speaks at an America First Rally in Chicago.

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The noninterventionists were so busy trying to stop America from entering the war across the Atlantic that they gave little thought to events in the Pacific. Japan’s surprise attack on U.S. naval forces in Pearl Harbor on Dec. 7, 1941, ripped the carpet from under the feet of Robert Taft and the American First Committee. In his diary, Lindbergh wrote that if he were in Congress, he would vote to authorize war against Japan. Senator Taft voted yes, and America First disbanded soon after the attack. (Hitler declared war on the U.S. on December 11.)

In its protectionism, resistance to immigration, religiosity, and antipathy to foreign entanglements, Donald Trump’s Make America Great Again movement resembles the conservatism of the 1920s—with one significant difference. In the 1920s, the right was in charge. It was self-confident and prosperous. It saw itself as defending core American institutions.

A century later, in the early 2020s, the right has been driven from power at the federal level. It has been locked out of the commanding heights of American culture: technology, media, entertainment, the academy. Its rhetoric has often veered into apocalypticism and conspiracy theory.

Parts of the right today look a lot more like the populist Democrats of William Jennings Bryan—who rallied under one banner all those who felt excluded from or dispossessed by the economic, social and cultural powers of his time—than the business-friendly Republicans of Coolidge. This combination of cultural estrangement and economic insecurity has made today’s Republicans much more open to government intervention in the market than their forebears.

Harding and Coolidge stood for “normalcy” and “Americanism.” Even when he was president, however, Trump stood outside the system in an era when the definition of Americanism is up for grabs. Trump didn’t maintain the status quo. He challenged it. He rebelled against expert opinion, political correctness, media narratives and the ways of the Washington “swamp.”

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Furthermore, Coolidge was distinctly American in philosophy and outlook. While Trump’s biography, celebrity and aesthetic are the elemental stuff of American popular culture, he more closely resembles national populist leaders in Europe, the Middle East, South America and Russia. In all these places, opposition to immigration and global trade, religious traditionalism, and strongmen with personal followings define the right.

From the vantage point of the pre-World War II era, such tendencies on the American right aren’t surprising. It too sometimes embraced demagogic leaders who pulled it toward the political fringe. What mattered then and still matters today is the willingness of intellectuals and politicians to confront and suppress the extremes. One way to think about the history of the right over the last 100 years is as a running battle between the forces of extremism and the conservatives who understood that mainstream acceptance of their ideas was the prerequisite for electoral success and lasting reform.

As the GOP has returned to its early 20th-century roots, it has struggled to persuade Americans that its agenda and spokesmen are within the mainstream. The right has benefited more from the false steps of its opponents than the popularity of its own ideas and leading figures. All of which might give Republicans pause as they embrace the changes brought about by Donald Trump and look forward to the midterm election this November. After all, the GOP enjoyed tremendous success during the 1920s—and then spent the next 40 years in the political wilderness.

—Mr. Continetti is a senior fellow at the American Enterprise Institute. This essay is adapted from his new book, “The Right: The Hundred Year War for American Conservatism,” which will be published by Basic Books on April 19.