I highly recommend this article by Allan C. Brownfeld, editor of the American Council for Judaism’s publication Issues.  The gist:

The fact is that there is no Jewish vote — only the votes of millions of individual Jewish Americans. These ballots are cast on the same basis as are those of Americans of other faiths. It is a dangerous challenge to our democracy to try to divide voters on the basis of religion, and to do so on the basis of a false picture of U.S. Middle East policy is harmful to all — to Israel, to the Palestinians, to American interests in the region and, perhaps most important, to the truth itself.