Leo P. Ribuffo, a scholar of American political history who specialized in examining the rise of the far right, arguing that mainstream historians had underestimated and misunderstood its influence, died Nov. 27 at his home in Washington. He was 73.

The cause was hypertensive atherosclerotic cardiovascular disease, said a friend, Bruce Rich.

Dr. Ribuffo, a professor at George Washington University, was widely known among academic historians for his 1983 book, “The Old Christian Right: The Protestant Far Right From the Great Depression to the Cold War.” It won the Merle Curti Award from the Organization of American Historians for the best book of the year in American social or intellectual history.

Writing in the New York Times in 2017, historian and journalist Rick Perlstein called Dr. Ribuffo foremost among a handful of historians to counter long-prevailing views in academia about the far right and its appeal.

“Irascible, brilliant and deeply learned,” Perlstein wrote, “Ribuffo argued that America’s anti-liberal traditions were far more deeply rooted in the past, and far angrier than most historians would acknowledge, citing a long list of examples from ‘regional suspicions of various metropolitan centers and the snobs who lived there’ to ‘white racism institutionalized in slavery and segregation.’ ”