I just had to relearn how to post links (whew!), but here's an excellent column by Dennis Prager that provides an answer to your question. I'd been wondering the same thing, and this column made sense.
Hmmmmmm....
" just don't get it. Why does any Jewish person choose to be liberal? It's self-defeating."
My family and my wifes family are all Brooklyn Jewish LIberals. My parents used to be liberals and I was a liberal as a college student. Not sure why, but when I went into the service, my position changed and one day my dad came home and said he had enough after Abe Beam raised taxes.
We both sakd screw it and moved our families to Texas. My in-laws are still in Jersey, bitching and moaning about high taxes and they will still vote for Corzine. I have no sympathy for them.