Is Safire missing something?

William Safire can't seem to figure out why, while Arab Americans are for Kerry, Jewish Americans are not turning to Bush in equivalent numbers. He looks only toward the candidates' attitudes towards Israel, and to traditional Jewish support for the left. I can't help wonder if the fact that Kerry has at least one Jewish grandparent ought to be factored into any of this. If a candidate who had one black grandparent were running for president, any discussion of said candidate's appeal to black voters would surely focus on his ancestry. I'd imagine that candidates hope to win not only their home states, but also their home demographic groups, and that they frequently win both. Ideally, a candidate's ancestry would never come into play, but it's assumed (by Safire in this op-ed) that Arab- and Jewish Americans are influenced by their own backgrounds; might the fact that Kerry, though Catholic, has a vaguely Jewish background, have something to do with why, despite his being the potentially less pro-Israel candidate, he's likely to get the "Jewish vote"?