That is a good question. There are many historical reasons why Jews are liberals. The Jewish community in the United States is about 80% Democrat and 20% Republican.
I have a feeling that those numbers will change over the next few years when the Jews finally realize that the Democrats will allow more harm to come to the Jews and Israel than the Republicans will.
My doctor is a Jew and conservative. He always laments to me how 95% of the people in his temple are liberal Democrats. (He knows what an activist I am.)
Of course, that was last year. I go in for my physical next Tuesday and it'll be interesting to hear how many of those same Jews have 'seen the light' since 9/11!