In the 1930s Jews formed an extremely disproportionately high percentage of the American Communist Party. The percentage of Jews that fought on the Communist side in the Spanish Civil War was similarly high.
The U.S. Jewish population today is composed of the sons, daughters, and grandchildren of these folks.
Don't expect them to vote for G.W. Bush, or any Republican any time soon.
Let's not forget there are many Jews, particular Russian emmigrants, that are rabidly anti-communist, most of which are very pro-Bush.
David Horowitz is a child of these same communist parents and he has realized the perfidy of communism. Today he is certainly one of the most prominent anti-communists and pro-Republicans in the country.
There are quite a few just like him. They are just not as visible as the Barbra Streisands.
Older Jews remember the anti-Semitism of pre-World War Two in the U. S. (Remember Henry Ford and Charles Limburgh, as two examples). They loved FDR and have never forgotten him and have voted Democrat ever since.
Younger Jews don't have those memories or those loyalties. They are not locked in to the Democrat Party and more will be voting Republican in this election and in future elections.