What would it have (realistically) taken for the GOP to win 1940/1944?

[Wisconsin SC Race 2019]

The economy was still sluggish from Depression after-effects, there began to be fatigue from the New Deal, and isolationism/war was raging all over...yet we know the Republicans couldn't seal the deal. What would it have taken for the GOP to knock FDR off in the elections? No alien abductions/magic/assassinations/etc., pls. Stay within the bounds of what was possible in this era.   

[dw93]

Honestly, FDR did consider not running in 1940, just have him follow Washington's precedent and not run.

[morgankingsley]

1944 is not all that hard. Have him relentless attack FDR for his health, Truman for his age, and the need to have a younger face take care of the end of the war and that we didn't need a man in awful condition to be in office at this time and have him really campaign hard on the idea that it was now the republicans turn to take the mantle again and that they were now reformed away from the depression party. Oh and have him shave his mustache lol. All he needed was Michigan, Pennsylvania, New Jersey, Illinois, Idaho, New Hampshire, Maryland, Oregon and New York and he wins the election despite losing the popular vote. It sounds like a lot, but many of those are big electoral powers and many of those were decided by margins of less than three percent and all but New York was decided by less than five