More than the fact that nobody's contacted me to give me my cut yet, it's polls like this that convince me that there really can’t be any Jewish conspiracy.

It's really difficult for me to understand how anybody could look at what Clinton did to Israel (leveraging aid in order to push Israel into making concessions; intentionally snubbing Bibi on the eve of the election by not sending Albright to Israel during her Mideast trip; all but directly campaigning on behalf of Barak; bringing Arafat to the White House (!!)) and think that either Kerry or Gephardt, both of whom are to the left of Clinton on Israel, would be better than Bush. That's before we even get to Howard "Palestinian suicide bombers are legitimate soldiers and we should be even handed towards them" Dean!!
The answer that I usually get when I talk to liberal American Jews about this is a they-doth-protest-too-much style "well, some of us care about more than just Israel." Which is fine, but the implied ad hom is against a strawman. It's not so much that liberal American Jews care about social issues that bothers me - it's that they apparently care so little about Israel that they're willing to let even marginal differences on social issues outweigh enormous differences on Israel. Also, judging by a couple of the answers below, I don't think that most of them have the first clue about what the Bush policy towards Israel actually is.
The more honest response is that these voters simply don’t care all that much about Israel. Sure, they’ll occasionally throw some money into the Magen David Adom tin around the High Holidays (if they even bother showing up to shul) but mostly they’re happy in their cushy Western, suburban lives. Frankly they even kind of resent all of the noise that those stubborn Ashkenazis over in that desert are making. Which would also be fine, but for the abysmal failure of any assimilation strategy to ever do anything but inflame violent anti-Semitism.
More fun and self-destructive beliefs held by American Jews:

The "we want France and the UN to dictate American policy, because we trust them to do the right thing for Jews" result:

Fifty-four percent of those polled disapprove of how Bush has handled the fight against terrorism and the U.S.-led war on Iraq, while a majority said the United States should not act without the support of its allies in responding to international crises.

The "we haven't watched the news or picked up a newspaper in the last 3 years and are therefore completely unaware of demographic or political shifts" result (The religious right? In quotes? What does that even mean?):

Nearly 70 percent said anti-Semitism was a greater threat to Jewish life in the United States than intermarriage, and said that among U.S. religious groups, Muslims and the ``Religious Right'' were the most anti-Semitic.

And finally, the "no, seriously, not once in the last 3years; in fact, we have no idea what Bush thinks about anything" result (remember, this is supposed to be a reason to oppose Bush; fun game - what part of this is not Bush policy):

Sixty percent said they supported how the Israeli government has handled relations with the Palestinian Authority, while 54 percent said they favored creating a Palestinian state.

Oh, and this is just too bad:

The poll omitted Democrats Carol Moseley Braun, John Edwards, Dennis Kucinich and Al Sharpton because they were not considered strong candidates, the New York-based public policy group said.

I would really have liked to see where Al "Jews are Diamond Merchants" Sharpton ended up. Probably pretty high, considering the disgusting willingness of liberal American Jewish groups to excuse even his violent anti-Semitism if it serves their narrow partisan interests. Remember how Abe Foxman, at a Clinton White House dinner, excused Sharpton on the grounds that "while Sharpton may have dabbled in anti-Semitism, he is not an anti-Semite"? What exactly does a member of the Democratic party have to do in order to get called out? Do they actually have to carry around a card with a swastika on it? Anything not to change American Jews' blind loyaly to the Democratic Party, I guess.

UPDATE: JPost has an article by Calev Ben-David on this very question. It's mostly a rehash of the poll, but he does make this interesting predication:

If Dean does win the nomination, you can be sure he'll try to whittle down Bush's 30 percent of the Jewish vote by stressing his support for the Jewish state.
I also wouldn't be surprised if we saw more of Dean's Jewish wife, Dr. Judith Steinberg-Dean, who's been virtually invisible on the campaign trail until now, or even hear more about how their two children were raised Jewish.