From Richard Pipes’ review of Stalin: Volume I: Paradoxes of Power, 1878–1928 by Stephen Kotkin:
[Trotsky’s] other handicap was his Jewishness. Although born a Jew, Trotsky attached no significance to this fact, on one occasion telling a Jewish delegation that he was not a Jew but an “internationalist.” Yet whatever he thought of himself, he was perceived, in and out of the party, as what Stalin in a personal conversation cited by Kotkin called “a Jewish internationalist.”