There were liberals in America who supported them. Sean Penn's father for one. I guess we can excuse them however because they didn't do it on their own. Joe Stalin told them to agitate against helping Churchill fend of Nazi Germany because the USSR and Nazi Germany had signed a non-aggression pact. There were liberals at the time who went on strike at munitions plants to slow down arms shipments to the UK.
I know of no liberals who supported the Nazis during World War II. There were some ultra-liberals who were fellow-travelers who supported Stalin. When Stalin allied himself with Hitler in 1939, some of these ultra-liberals marched against American involvement in World War 2. But that evaporated overnight when Hitler attacked Russia in 1941.
If they seemed to be “siding” with the Nazis it was only because Stalin had ordered them to tow the Soviet line during 1939-1941.