In his 1955 Pulitzer Prize-winning book The Age of Reform, Hofstadter painted a much different picture of the original populists than had previously existed, arguing they were conspiracy-minded nativists and anti-Semites. For Hofstadter, populists were forerunners not of modern liberalism but of right-wing movements like McCarthyism. "My own interest has been drawn to that side of Populism and Progressivism—particularly of Populism—which seems very strongly to foreshadow some aspects of the cranky pseudo-conservatism of our time," he wrote (by "pseudo-conservatism," he meant McCarthyism).

Alan Brinkley of Columbia University described The Age of Reform as “the most influential book ever published on the history of twentieth-century America.” Yet its influence has been a curious one. For many educated Americans, it remains the main prism through which populism is understood. As historian Walter Nugent wrote in a 2013 preface to his 1963 book The Tolerant Populists, Hofstadter stood at the head of a revisionist scholarship which argued that “the 1890s Populists were the forerunners not of liberal movements but of nativism, anti-Semitism, the rants of radio priests Charles Coughlin in the 1930s and of Joseph R. McCarthy and McCarthyism in the 1950s. Until then, ‘populism’—with a small p—was not a dirty word. But it became one, and it has continued to carry the connotation of demagogic, unreasoning, narrow-minded, conspiratorial, fearful attitudes toward society and politics.”

Rare among historians, Hofstadter was a beautiful writer, which explains why his books have continued to shape perceptions decades after they’ve been released. But he wasn’t much of a researcher. As he once said, he considered himself “as much, maybe more, of an essayist than an historian.” His ideas about the populists rested on a very thin dive into the archives. While The Age of Reform enjoyed a brief vogue among fellow scholars after its initial publications, there soon emerged a strong, heavily researched literature that revealed it to be a deeply flawed text—that almost all of Hofstadter’s claims about both populism and McCarthyism were wrong, analytically and factually. Nugent’s work and Lawrence Goodwyn’s Democratic Promise, which were based on a much more thorough and systematic archival research, demonstrated that the original populists were not particularly bigoted or nativists. As historian Michael Kazin argued, summarizing this authoritative literature, anti-Semitism “a minor element of the movement’s language.” Actual hatred of immigrants, African-Americans, and Jews was as likely to be found among elite opponents of the populists.

If the original populists were not particularly bigoted, subsequent bigots were not particularly populist. In a 1955 essay for a book called The New American Right, Hofstadter blamed the rise of Joseph McCarthy on the fact that “in a populistic culture like ours, which seems to lack a responsible elite with political and moral autonomy... it is possible to exploit the widest currents of public sentiment for private purposes.” But the political scientist Michael Rogin, in his 1967 book The Intellectuals and McCarthy, showed that Hofstadter and other 1950s scholars were simply wrong in their understanding of the anti-communist demagogue. Using a sophisticated public polling data and a reexamination of McCarthy’s career, Rogin proved that far from being a product of a populist mass movement, McCarthy’s locus of support was the traditional Republican Party base of business owners, particularly those in small and medium-sized cities. McCarthy appealed to the business elite because his anti-communist crusade promised to roll back the New Deal and newly empowered labor unions. He, no less than Donald Trump, was the voice of aggrieved privilege, not the champion of the common person.