After resigning as head of the CIO in 1941, he took the Mine Workers out of the CIO in 1942 and in 1944 took the union into the American Federation of Labor (AFL). Lewis was a Republican, but he played a major role in helping Franklin D. Roosevelt win re-election with a landslide in 1936, but as an isolationist supported by Communist elements in the CIO, Lewis broke with Roosevelt in 1940 on anti-Nazi foreign policy. (Following the 1939 German-Soviet pact of nonaggression, the Comintern had instructed communist parties in the West to oppose any support for nations at war with Nazi Germany).).