February 24, 1940
President Franklin D. Roosevelt (D) Forgoes a third term
"Despite the pressing matters that face the world today, I make this decision by the interests of my family. I shall not break the tradition set in place by our founder, George Washington, and run for a third term. It is simply not in me to do so" - Roosevelt, in a press conference regarding the matter
Many individuals, from the Vice President to minor representatives, hop into the race. The key front-runners were Vice President John Nance Garner, Secretary of State Cordell Hull, and Secretary of Agriculture Henry A. Wallace.
Wallace?????
Not in a million years. He was a Republican who had never run for any office. When Roosevelt tabbed him for Vice President, the convention balked
hard. Roosevelt had to threaten to withdraw as nominee to get Wallace nominated with him. Wallace had no organization, and AFAIK no Presidential ambitions.
The lacking campaigning skills of Hull, paired with him being at odds on occasion with Wallace, and the true strength of Willkie and his campaigning skills...
Hull was a political veteran: two terms in the Tennessee legislature, 11 terms as US Representative, and election as US Senator in 1930.
Willkie was a political novice. As to his campaigning skills, I will cite the opinion of SF writer Robert Heinlein, who was very active in politics in the 1930s and 1940s. He distilled his experience into a handbook of practical politics, written in 1946 but not published till 1992. Heinlein especially warned against running a first-time candidate in an important race, and cited Willkie's performance in 1940 in support. According to Heinlein, the reporters who covered Willkie's big campaign tour agreed that Willkie hurt himself on almost every occasion.
...Willkie winning a landslide...
Willkie might have won - but this shows a
20% swing in the vote. Granted, Hull is not Roosevelt - but he also is not running for a third term. This might be possible
if the Democrats nominated Wallace (but see above), and the Republicans hit him with the "Dear Guru" letters (
and something stops the Democrats from exposing Willkie's adultery with Irita Van Doren in reprisal).
Even so... The map shows Willkie winning CA, WA, NV, AR, UT, MT, KY, and MD - all states which Willkie lost OTL by at least 15%.