A Christian theocracy is a bogeyman of more than a few people on this list; in the past year I've seen two or three threads about it. And given the foibles of current Western politics, overblown fears of Muslim theocracy can be branded as racist, overblown fears of Christian theocracy cannot. (Nevermind that there's a lot more socially conservative Christian fundamentalist African-Americans than people think; and that Hispanic immigrants are mostly Roman Catholic, and often more serious about it than native-born Catholics. I would not be surprised if the Democratic Party is headed for another rupture in its base a decade or two down the line.)
Back to the thread topic--a conservative GOP-voting Jewish population is unlikely, but not quite ASB. In OTL, many of the most influential original neo-conservatives were Jewish.
Perhaps: Israel loses an Arab-Israeli war, and much slaughter occurs. Jewish politics in the U.S. become, not so much socially conservative, but very hawkish. Since the mid-1960s, the Republican Party has been the more hawkish party. And there you go.