Reason that a Jewish population might have supported the creation of Israel by the Mid 1940s is Antisemitism in Europe as revealed in the horrors of the holocaust.
Explanation:
After the end of world war the allied powers won the battle and Britain and other European countries asked Germany to sign the treaty of Versailles which was a forceful document of peace. The clause of the treaty intended Germany to solely bear responsible for instigating the bloody and violent world war and also charged huge war reparation charges which shook the economic stability of Germany.
Nazism founded by Hitler could not bear the pressure politics as the treaty was such a disgrace to Germans. Hence, Under the regime of Hitler, many Jews who followed Judaism were either forced to christian conversion or they were exterminated in mobile killing units and concentration camps. More than four millions of Jews were killed due to huge hatred towards the European originated Jews. Antisemitism and cases based on this racial disparity is still prevalent today.