Franklin Roosevelt's election ended a long period of Democratic futility in national politics. Between William McKinley's election in 1896 and Herbert Hoover's defeat in 1932, only one Democrat—Woodrow Wilson—occupied the White House. And Wilson only won because his two Republican predecessors, Teddy Roosevelt and William Howard Taft, ran against each other in the election of 1912, splitting Republican support and allowing Wilson to sneak in with a plurality of the votes.
Roosevelt's 1932 victory was due more to disgust with Hoover than to enthusiasm for the Democratic program. Through the implementation of the New Deal, FDR was able to construct a new political coalition that created a solid Democratic majority that would endure for a generation.
The New Deal coalition began with the Democrats' traditional core of support—the "Solid South," where traditionalist Southern whites still resented the Republican Party for its leading role in leading the North to victory in the Civil War and destroying slavery. Southern Democrats' conservatism made for an awkward partnership with Roosevelt's progressive agenda, but the "Solid South" did heavily influence the New Deal by setting certain boundaries beyond which Roosevelt could not go without upsetting his coalition. The New Deal's very mixed record on race, for example, is largely due to Southern Democrats' leverage in blocking progressive measures to benefit African-Americans.
The other groups that comprised the New Deal coalition—trade unionists, farmers, city-dwellers, minorities, and liberal intellectuals, all beneficiaries of federal programs—tended to be more simpatico with Roosevelt's progressive instincts.
New Deal legislation provided, for the first time, government protection of the rights of workers to organize unions, allowing the unionized population to skyrocket from 11% of the workforce in 1930 to an all-time high of 35% in 1945. The labor vote has been heavily Democratic ever since.
Roosevelt's measures to prop up farmers were far from perfect, but they still went farther than any previous president had gone to address agricultural grievances that dated back to the nineteenth century. A large bloc of progressive farmers, epitomized by FDR's Secretary of Agriculture (and later Vice President) Henry A. Wallace, offered fervent support to FDR and his agenda.
Much of the New Deal's relief spending was funneled through liberal and Democratic political machines in the nation's large cities. That spending sustained huge patronage operations and won devoted adherents among the large populations of blacks, Catholics, Jews, and other ethnics who inhabited America's metropolises, and who came to view the New Deal as a lifeline in a time of industrial collapse. Roosevelt won further support among his urban boosters for his role in ending Prohibition, which had always been a policy pushed by rural conservatives.
Roosevelt's New Deal Coalition was not without its tensions; the divide between conservative Southerners and progressive Northern urbanists had wracked the Democratic Party for decades, and would continue to bedevil the coalition until the Southerners finally flipped to the Republicans in the wake of the Civil Rights Movement of the 1960s. Still, through the magnetism of his personality and the largesse of his programs, Roosevelt was able to hold the coalition together to create a Democratic majority that endured for decades. Between 1932 and 1968, the Republicans elected only one president, war hero Dwight Eisenhower. Even more remarkably, the Democrats maintained control of both houses of Congress for all but four years from 1932 to 1980.
It was an impressive achievement for a politician once dismissed as "a pleasant man who, without any important qualifications for the office, very much would like to be president."