If the Jews left the Democrats and joined the Republicans, just think how venomously the Democrats would label the Republicans as a Zionist conspirators. Maybe the Jews see themselves more secure with the Democrats to avoid such.
This much is true. One thing that is rampant among Jews that I have been friends with is anti-Christian hatred. I sit there stunned with some of the things they say. And it is a pure hatred. The republicans welcome believing Christians. Therefore in a Jewish mind, republicans are evil. Plus Hitler supposedly was a "right-winger" and a lot of them think that only liberals will oppose the "right-wing" conservatives.