As a young man Ronald Reagan was an FDR Democrat.
When he switched to Republican and endorsed Barry Goldwater he said “I didn’t leave the Democrats. The Democrats left me.”
Reagan significantly never said that he regretted voting for FDR. And after he became a Republican he never criticized FDR.
You’re quite right about Wendell Wilkie being an ideological twin of FDR when he ran on the GOP ticket in 1940. Probably not a huge surprise since he had been a Democrat until 1939.
Robert Taft had been the conservative challenger to Wilkie in the 1940 GOP primary. The GOP has rarely run conservative candidates.
The only Conservative Canidate the GOP ran from 1932to 1952 was Dewey in 1944, who got beaten because of the war. Eisenhower ran as a Conservative, but govenered as a Moderate.( A somewhat Conservative today. JFK was a Moderate to Moderate Liberal then, today he would be Conservative. HE EAS FOR THE GOLD STANDARD!
Taft did not have the charisma. John Bricker of Ohio would have been a great canidate, he would have taken it to the commie-codling Socalist Rosevelt.