Lindbergh would probably be too controversial assuming the situation in Europe is similar to OTL. Yes, there was a lot of isolationism in the country and in the GOP, but Lindbergh's outright sympathy with the Nazis was arguably a step too far even for the mainstream of the GOP.
Also, while Taft is certainly a possibility, people shouldn't rule out Dewey as the nominee. Yes, he was young (38), and only a DA, but he was actually the frontrunner for the GOP nod that year. He was already a national celebrity, and came from a hugely important swing state (New York) - for a GOP that was desperate for a win, he might well have gotten the nomination, particularly over Taft who was seen as too conservative and too Midwestern to appeal to more New Deal-friendly states.
Dewey/Vandenberg, perhaps?
ON EDIT: I should point out that the most obvious way to get FDR out of the 1940 race is for war to have not broken out in Europe or for the crisis to have been resolved earlier. That could be anything from one of the assassination attempts on Hitler succeeding, France invading Germany in response to Rhineland militarization, or war breaking out in 1938 and being resolved without U.S. involvement. That means no FDR third term, no Willkie groundswell, and a presidential campaign focused on domestic affairs.
Also, while Taft is certainly a possibility, people shouldn't rule out Dewey as the nominee. Yes, he was young (38), and only a DA, but he was actually the frontrunner for the GOP nod that year. He was already a national celebrity, and came from a hugely important swing state (New York) - for a GOP that was desperate for a win, he might well have gotten the nomination, particularly over Taft who was seen as too conservative and too Midwestern to appeal to more New Deal-friendly states.
Dewey/Vandenberg, perhaps?
ON EDIT: I should point out that the most obvious way to get FDR out of the 1940 race is for war to have not broken out in Europe or for the crisis to have been resolved earlier. That could be anything from one of the assassination attempts on Hitler succeeding, France invading Germany in response to Rhineland militarization, or war breaking out in 1938 and being resolved without U.S. involvement. That means no FDR third term, no Willkie groundswell, and a presidential campaign focused on domestic affairs.