Karma, as an Israeli for most of my life, I may be displaying ignorance (or just not being up-to-date), but I think the problem Jews have with American politics is it's a package deal.
You know about the Israeli Jews' rightward shift. When the J14 demonstrations broke out in Israel, in protest of privatization that left many people without the means to afford even rent, observers outside Israel from the Left and Right alike were puzzled: If Israel has shifted right, said the American right-wingers, how is it hundreds of thousands of Israeli Jews are demonstrating for the continuation of the socialist welfare state? Conversely, the American left-wingers asked, if Israeli Jews are overwhelmingly left-wing, as the J14 demonstrations show, how is it they're so hawkish on their relations with the Arabs?
As an insider, the answer is obvious: "Left" and "Right" in Israel aren't package deals; the massive rightward shift among Israeli Jews in the 2000s was only about the Jewish–Arab conflict, not economics. So you easily get a hybrid left-on-ecomonics, right-on-foreign-policy Israeli Jewish public.
But in America it looks like a package deal. "Right-winger" means the whole shebang of hawkish foreign policy, fiscal conservatism and (though less so ever since 2008) social conservatism; "left-winger" means socialism, blame-America-first and increasingly anti-Zionism all integrated into one big box.
So there's an American Jew who realizes, like you've done, that the "Progressive" Left is getting to be antithetical to Jewish well-being, but he still believes in the welfare state. If he were an Israeli Jew, he'd have no problem: Defect to the Right in foreign policy matters, keep going to pro-socialist demonstrations on the economy. But an American Jew is in a bind: Hybrid politics, it seems to me, aren't appreciated in the U.S. of A.
Just my 2 agorot.