Many left-wingers in the '30s and '40s actually did sympathize with Hitler. Of course they kept quiet about it once the genocide was exposed.
No, that was right-wingers who were Hitler fans in the 30s and 40s. It cannot POSSIBLY have been leftists, because he killed all he could and threw out of work and out of Germany as many of the rest as possible. This was well-known because of all the refugees in Paris and other places and they wrote a lot about it.