According to this story, the answer is that the two most Republican-leaning segments of the Jewish community, Orthodox Jews and “Russians,” are younger on average than other Jews. And I would add that the effect is likely understated, because Haredi/ultra-Orthodox Jews are unlikely to be reachable by pollsters, and the more recent Russian immigrants have a language barrier.
Another interesting tidbit from the article is that 80% of young Jewish women voted for Kerry, compared to 60% of young Jewish men. Anecdotal evidence suggests that, moreover, while there are a significant number of young Jewish Republican men who are active in politics, (and for that matter, there are many male Jewish libertarian activists) almost all young Jewish women who are political activists are Democrats or otherwise on the left.
“Professor Joshua Comenetz from The University of Florida says the Ultra-orthodox population doubles every 20 years, which he says may make the Jewish community not only more religiously observant but more politically conservative.
“Comenetz estimated the Ultra-orthodox population in 2000 was about 360,000, 7.2 per cent of the approximately 5 million Jews in the U.S.
“But in 2006, demographers now estimate the number had grown to 468,000 or 9.4 per cent.”
That sounds like a high estimate to me, but I haven’t seen any good demographic studies. But last time I was in the Haredi neighborhood of Williamsburg, Brooklyn, I was amazed at its vastness, compared to just twenty years ago.