Unlike earlier studies of the 1948 election, Truman Defeats Dewey examines the tactics of the Republican Party. Donaldson argues that Dewey did nearly as much to lose the election as Truman did to win it. Dewey entered the campaign so overconfident that he refused to confront Truman on the issues. The Republicans, certain of a mandate from the public after the midterm elections of 1946, prepared to disassemble the New Deal. Yet they suffered from even more severe internal division than the Democrats.

The 1948 presidential campaign was a watershed event in the history of American politics. It encompassed Truman's rousing "Give 'em Hell Harry" speeches and intriguing behind-the-scenes political maneuvering. It was the first election after Roosevelt's death and the last before the advent of television. It marked the new political prominence of African American voters and organized labor, as well as the South's declining influence over the Democratic Party.