The first bad omen in Tom Wicker’s “One of Us” comes in the preface. (The second, if you count the ponderously uninformative subtitle.) Wicker makes it perfectly clear what his book isn’t: “[It] is not a biography, nor is it a comprehensive account of Nixon’s career, or even of his presidency. It is too factual to be a speculation and too speculative to be the last word.” But he can’t quite say what it is: it’s not just about Nixon, he claims, but about “American politics, American lives, American dreams, American reality.” Would you buy a used cadence from this man?

But whatever it is, “One of Us,” in stores next week, will be required reading for diehard Nixon buffs. Not because it’s one more measured assessment - recent Nixonographers, like Stephen Ambrose and Roger Morris, no longer make overwrought allusions to Richard III - but because Wicker, distinguished reporter and best-selling novelist, once conspicuously graced Nixon’s “enemies list.” Journalists, Nixon wrote in a presidential memo, “have a fetish about fairness, and once they are caught being unfair they. try to compensate.” Wicker covered Nixon for The New York Times from 1960 on and admits he “was more often his critic - in retrospect, not always knowledgeably - than his admirer.” Maybe “One of Us” is his penance. From title to peroration (“Which of us. has never cut a corner or winked at the law?”), he worries more about “our” hypocrisy than Nixon’s.

Americans, writes Wicker, want the White House to be “a place of moral purity and disinterested public service,” yet the presidency is “essentially apolitical office, functioning best in the hands of an astute politician.” Like him or not, Wicker argues, Nixon was that - until his “fetish for secrecy” undid him, “not just ultimately in Watergate, but in the widespread lack of support and good will of a public that could seldom see his world vision because of the ‘crafty atmospherics’ that beclouded it.”

So in hindsight, the Checkers speech swells to “a moment of courageous personal achievement”; the Huston Plan (authorizing wiretaps and break-ins) dwindles to no big deal. Nixon becomes the great centrist: his domestic record, from desegregation to the environment, now looks a little better than most presidents’, and his lies and abuses of power not much worse. Just because we’ve heard this before - in Nixon’s own books, for instance - doesn’t mean it’s not true. What’s odd is that Wicker doesn’t find it more depressing.