A this-is-your-political-life gander at youthful Representative Pete McCloskey, the man with the Jack Charisma profile who's sniping primarily at Nixon's left in New Hampshire and, who knows, maybe beyond. At any rate that's the challenge (also enunciated in the candidate's own literature, Truth and Untruth, scheduled for publication next month), but columnist Cannon is more interested in what makes Pete push -- and to find out he talks to McCloskey himself (who was ""candid beyond call""), his wife Cubby (who said ""the best thing about him is his ribald, small-boy sense of humor""), relatives, boyhood chums, political friends and enemies. Cannon's announced intention is a ""balanced"" biography (he's done this sort of thing before -- Ronald Reagan, Jesse Unruh) which is accomplished by heavy-handed reliance on but-on-the-other-handers -- for instance, McCloskey's campaign against Shirley Temple Black was masterful but. . . ""it was McCloskey who panicked in the last days of the 1968 primary."" However, despite all of this effort at objectivity, Cannon is unable to hide his fundamental sympathy for the congressman and his cause. If McCloskey gives the President a run for the votes in the Republican primaries, this might have an audience. But until that time, it's just unpaid advertising.