The Left actively supported Hitler's Nazi Party and created a Moscow directed and funded “Peace Movement” in this country that agitated to keep the US out of the war in Europe so Hitler and Stalin could crush Europe and Asia and co rule the world to together with some token tolerance for the Japanese.
Roosevelt's VP Henry Wallace was an open and enthusiastic supporter of Stalin and of Soviet Communism from the 1920’s onward.
Wallace was officially a Progressive and in a visit to Russia in 1941 he was given a tour of the horrible gulag camp at Magadan.
Wallace was filled with enthusiasm by what he saw in Soviet Russia and in the gulag because he found such a powerful coercive tool to impose his progressive agenda on people.
At the end of World War II, it ha=s been revealed by historians such as Allen Weinstein that Wallace even went so far as to arranged secret meetings with the Stalin's chief spy and NKVD Washington station chief, offering him access to American scientists working on the atomic bomb.