Why did FDR lose support in 1944 (compared to 1940)?
Because of these facts, I would suspect the opposite to happen:
- first, and most important, WW2 was in its closing stage as of November 1944. The president led the nation through the war and now to ultimate victory.
- the economy was finally in a good shape
- Wendell Willkie had been a stronger campaigner than Tom Dewey.
- the unwritten law not to serve more than two terms was already broken.
Possible ideas:
1.People accepted the idea of the two term limit being broken during a war, but not as the Peace became clear.
2.FDR's declining health was quite apparent by 1944 and was also the reason why Henry Wallace was dropped as Vice President, though I doubt the public knew that was the (main) reason.
3.I believe there were already increasing incidences of corruption in the Democratic Party, though I don't believe that became a major issue until Truman became President.
4.A general feeling of 'time for change.'
5.Wendel Wilkie may have run a better campaign than Dewey, but Dewey was, as a New York Governor, likely a more acceptable alternative as President than a guy who had never held elected office, and who, iirc, had been a supporter of FDR only a few years earlier.