Jews have a hard time voting Republican because after war, FDR supported them, and GOP was prejudicial toward them. Is that a true statement?
after war, FDR supported them,
Nope.
The passengers on the SS St. Louis might beg to differ.
Anyone who believes that FDR and the Democrats tried to help the Jews need only read about the 1939 voyage of the MS St. Louis. It truly was a Voyage of the Damned.
https://en.wikipedia.org/wiki/MS_St._Louis#The_%22Voyage_of_the_Damned%22