reporter: the tag was as good as the joke. my brother. reporter: one of america s best known comedians. who said tough room? reporter: far from being tough, for the comedian in chief, it was like picking low hanging fruit. jeanne moos, cnn, new york. lots of fun. i m wolf blitzer in the situation room. john king, usa starts right now. thanks wolf. a number of breaking developments at this hour. a counterintelligence official has just told cnn authorities can t rule out the possibility that a terrorist sleeper cell is behind the attack. but they don t know just yet. also a former member of the new york police bomb squad member tells cnn the suv had no known signature, meaning it wasn t built in a way used by known terror organizations. in a moment, you ll hear the chairman of the senate homeland security committee tell cnn he has no doubt this was a