Dan Fleischer has a very good post up regarding the severe discomfort some on the left (including some Jews) have with the prospect of Judaism as an identity (see also). It is personally infuriating to me, this deep, deep refusal to acknowledge Jews as legitimate political subjects. Any Jewish action is seen as some sort of illegitimate external interference, because the basic acceptance of the idea that we have a right to any sort of communal action or agency is denied. Indeed, it is seen as the antithesis of a certain (cheap) cosmopolitan ideal which is superficially hostile to all particularistic action, but particularly so (ironically!) towards the Jews -- I suspect because other communities are too powerful to have their preferred form of social presentation challenged in so frontal a manner. The dreaded Zionist Lobby only seems so visible because the true powerful communities don't need a lobby at all to preserve their legitimacy. Nobody has to stand before the UN and argue that China (or the Chinese, for that matter) has the right to exist.
This all is ironic as well because of the historical tradition within nationalistic ethos' where Jews are often portrayed as irredeemably uprooted and cosmopolitan, thus not full members of the community. Jews are too particular for the cosmopolitans and too universal for the particularists, because ultimately, the problem is with Jews being Jews, and for not having already attained the utopian dream of the speaker (a dream that always transforms from aspiration to demand when applied to the Jews).