You are correct. There was left wing opposition to the US entering WWII or even providing military aid to Great Britain, and other European countries until Germany invaded
the USSR on June 22, 1941 (Operation Barbarossa).
That was a major reason why France was so unprepared for war in 1940, and folded up as quickly as they did once Germany invaded. There was a strong Communist element within France, the Soviet Union and Nazi Germany were allies at the time, and they interfered with French rearmament at every turn.
Also, there was a strong admiration of Naziism among much of the French population; many saw it as a bulwark against the Communists, and also there was widespread admiration of Nazi Germany’s appearance of order and accomplishment of rebuilding a broken nation.
To be blunt, there was a great deal of rightwing opposition as well. Frankly I would say more than from the left.