The issue in 1940 -- the only real issue -- was isolation versus intervention.
Taft, Vandenberg et al were strong isolationists, while Wilkie was for providing more US aid to the allies.
Yes, as the fall campaign developed, in typical American fashion, both sides tried to appeal to all voters.
Eventually Wilkie accused Roosevelt of a secret plan to lead America to war.
FDR in tern suddenly discovered isolationism and promised he would "not send American boys into any foreign wars."
When war came in December 1941, all the Republican isolationists supported it.
When war came in December 1941, all the Republican isolationists supported it.
Foreign policy was a major issue, but not the only one. The economy was also a major issue, with Willkie making reference to "seven years of depression" under FDR. Willkie also made a big issue of the president's bid for an unprecedented third term.
Not every Republican supported the war when it finally broke out. Rep. Jeannette Rankin (R-Mont.) voted against declaring war--as she had done in 1917.