Alf Landon, 1936
The word "landslide" does not even begin to cover the scale of Landon's defeat. "Blowout," "massacre," "tidal wave," none of these are adequate. Imagine, perhaps, the planets Jupiter, Neptune, and Saturn all landing on top of Landon shortly after alligators, crocodiles, and other animals of a similar temperament have chewed, eaten, and digested Landon's body, and then been eaten themselves by another set of alligators and crocodiles, meanwhile a tidal wave comes in and carries the whole mess a way, and Landon gets a flat tire. Something like that. Landon did so little campaigning on his own behalf, that columnist Westbrook Pegler wondered if they shouldn't file a missing persons report. The Republican party, in a sudden burst of altruism, sent checks for $5 to 400 black pastors urging them to vote for the party of Lincoln, but to no avail. Landon lost in 46 of 48 states, including Kansas, where he was governor.
The reason, of course, was the magnificent success of the New Deal. In just four short years, Roosevelt had taken America from a devastating Depression with 24% unemployment rate to a booming, robust economy with a 20% unemployment rate. FDR had switched course on a campaign promise to reduce "unneccessary government agencies," proliferating them to such an extent, if must've provoked worry that a mere 26 letters in the alphabet would be insufficient to identify them all. One very popular program was a sort of annuity plan by which benefits would be paid to retirees from payroll taxes on those still working. In the private sector, this is known as a Ponzi Scheme; Roosevelt called it Social Security. Roosevelt also took the controversial move of placing former bootlegger and Wall Street operator Joe Kennedy in charge of the brand-spanking new Security Exchange Commision. Kennedy, however, was a great success at the post, knowing all the sneaky and underhanded tricks first hand, and reformed everything, so we haven't had a speck of trouble from Wall Street ever since.
Result
Franklin Roosevelt: 523
Alf Landon: 8