JOHN EHRLICHMAN thinks he can have it both ways. On the one hand he wants to persuade us that the erstwhile tough guy of the Nixon White House--the fellow who gave the language "twisting slowly, slowly in the wind"--has turned pussycat: living in Santa Fe with the artists and flower children, sporting a most peaceable beard, proposing to live benevolently among the Indians in lieu of imprisonment. But on the other hand the old tough guy still lurks not far beneath the carefully rehabilitated exterior, and that guy has some scores to settle; he settles them, with a vengeance, in Witness to Power.

This, presumably and mercifully the last of the "major" books to emerge from the Nixon administration and its sordid demise, is a mean-spirited, self-serving, nasty job of work--and a maliciously entertaining one. Bloodletting can be great sport; Ehrlichman did not lose his talent for it during his stay in prison, and here he sets about his business with the verve of a gladiator or matador. He tends more toward the bludgeon than the rapier; but whatever the weapon, the carnage makes for a dandy show. It is not necessary to agree with Ehrlichman's characterizations in order to be amused by them. A few samples:

* Robert Finch "was photogenic, could give a pretty good speech and had an easy smile. In Congress it seems to help if you're a little scattered and disorganized, and Bob Finch was that. He had no talent whatever for running a campaign, or running the Department of Health, Education and Welfare, or running anything else requiring much consistency and firmness."

* Julie Nixon Eisenhower "is quick-minded and articulate, a Richard Nixon in attractive packaging. If she thinks you are out to get her, she will come straight at you, smiling, either to charm you or to cut you off at the knees."

* Henry Kissinger "and his wife, Nancy Maginnes, are the tenders of a flame: the historical reputation of Dr. Henry Alfred Kissinger, the Nobel laureate. When last I saw them, in 1979, I had the impression that they stand four-hour shifts, alert to attack, shielding the flame with their bodies and souls."

* Shirley Temple Black "had become a matron of more than ample girth, and it was startling to see that memorable face from childhood movie matinees riding on a body from a girdle ad."

* John J. Sirica "was in a pell-mell rush to judgment that had nothing to do with judicial probity. It had to do with fame and public pressure."

* Warren Burger "looked like a judge, talked like a judge and, most important, wanted a seat on the Supreme Court so passionately that he would have agreed to almost anything to get it."

There's a gratuitousness to some of these slaps that is quite genuinely loathsome; often Ehrlichman introduces a person into his narrative (Shirley Temple Black, Wilt Chamberlain, Carl Albert, John Warner) for the clear and sole purpose of making fun of that person. Other slaps (John J. Sirica, John Dean, Lowell Weicker, Sam Ervin) are entirely predictable and thus lose a good deal of their sting; Ehrlichman's interest in getting back at those who wounded him is too obvious, notwithstanding the cloak of good humor and self-deprecation under which he attempts to hide it.

But there are three people whom Ehrlichman treats with what is, in the context, remarkable vagueness: H.R. Haldeman, John Mitchell and Richard Nixon. The relatively minor characters in this little drama lie on the floor in various stages of melodramatic dismemberment, but the major ones are shadows in the distance, only dimly perceived. Haldeman, the old and close friend who lured Ehrlichman into the Nixon camp in 1959, is treated with sympathy; the tensions that arose between the two men as their cases went to trial are effectively ignored. Mitchell, whose blunderings had much to do with Ehrlichman's eventual grief, gets scarcely a demeaning adjective or adverb. And as for Nixon, for whom Ehrlichman now claims never to have held especially deep feelings one way or the other, he is sketched only in the thinnest lines; the king, in his mighty courtier's portrait, is barely visible.

These three major omissions are all the more startling because Witness to Power is more about people than about issues or events. Unlike the accounts by Haldeman, Dean, Colson, Magruder et al., ad nauseam, this is not a "Watergate book"; less than one-fifth of it is devoted to Watergate, and in a rather perfunctory fashion at that. Ehrlichman describes the book as "primarily an account of people and events as I perceived them eight to 10 years ago," yet he short-changes the three central characters. Why he does so is a mystery; but charity-- considering the source--is an unlikely explanation.

What Witness to Power most emphatically has in common with the other Nixon books--Nixon's own, in particular--is that it is an apologia pro vita sua. Never before in the history of American letters have so many people spent so many pages attempting to exonerate themselves of so many transgressions. Unlike some of the others, Ehrlichman is too smart to try to pass himself off as a priest or an innocent victim; instead he has adopted the wily ploy of appearing in his own narrative as a reformed sinner who looks back upon the days gone by with a mixture of world-weariness, amusement and regret--though certainly not much of the last.

Ehrlichman suggests, for example, that he never had much of an ideological or even personal commitment to Nixon: "There were things about Nixon that I didn't like, of course. But by now (1967) I had an equity in his candidacy, and he was my only entr,ee into the big political game I had learned to play." The clear intent of this is to put some discreet distance between Ehrlichman and Nixon; but the actual effect is to reveal Ehrlichman as a cynical opportunist who would have hopped aboard any passing train if the schedule indicated that its final stop would be the White House.

Similarly, Ehrlichman attempts to portray himself, in his role of domestic-affairs spokesman within the White House, as a voice for moderation and enlightenment. He is at some pains to beat his breast over Nixon's record and attitudes on race: "That subliminal appeal to the antiblack voter was always in Nixon's statements and speeches on schools and housing, and it always bothered me. . . . Nixon said he believed America's blacks could only marginally benefit from federal programs because blacks were genetically inferior to whites. . . . I was appalled but not surprised." He was so "bothered," in fact, and so "appalled," that he went right on plucking all the strings of the "Southern strategy" and the various antiblack aspects of the Nixon domestic program. His after- the-fact dismay has the ring of blatant hypocrisy.

Here and elsewhere Ehrlichman, who has some prior experience at it, is laundering. In this case the object being cleansed is himself. He's an intelligent man and a crafty one; more rapidly than any of his Watergate accomplices, his b.ete noir John Dean possibly excepted, he recognized the profit to be gained by seeming to come clean and to cross over to the opposition. He's done Santa Fe and the beard and the Indians; he's written a couple of novels that view with obligatory dismay the abuses of power in Washington; now he's come forth with a memoir that offers contrition if not penitence.

But I for one am not buying. Ehrlichman strikes me from afar as a rather engaging chap, in a coldblooded way, and he is not a bad writer; his pride in refusing to hire the services of a ghost writer is amusing and justifiable. But it remains that Witness to Power is a cynical and distasteful book. Hunkered down in his hacienda Ehrlichman may indeed be the Republican answer to Charles Reich, but that hardly excuses or explains away the Ehrlichman who during his four years was no mere "witness" to power, as he now wants us to believe, but a quite merciless and amoral wielder of it. He tells us of his amazement at hearing the terrible things said on the tapes by Dean and Colson and others; he conveniently neglects to remind us that on many of the tapes there were many sleazy things said by John Ehrlichman, whose role in the coverup simply does not disappear under the mountain of words he has heaped over it.

For readers who enjoy the skillful use of invective, Witness to Power has its attractions. But there is nothing of real interest to it. Aside from the already-revealed charges that Ehrlichman makes against Warren Burger, there is little here of genuine news value. Ehrlichman claims that he turned down an offer of the attorney generalship: So what? Who cares?

Ehrlichman was a manipulator in the White House, and he wants to be one as a memoirist. He wants us to believe that with the exception of one very small slip-- "there was no question that I had known money was going to the burglars and I had abetted its flow"--he was an injured party who was unjustly vilified and convicted. But by the final page it's clear that he simply doth protest, and manipulate, too much. Witness to Power is a fraud.y