THOSE IN THE MOOD for a lovely wallow may find John Ehrlichman's White House memoir a bit of a dry hole. His forthcoming book, "Witness to Power," is 417 pages long, and it isn't until page 341 that he settles down to Watergate.

It's Ehrlichman's revenge. He knows the fans will be looking for the denials, the rationalizations and breast-beatings that are the stuff of Watergate retrospectives. So he makes them wait until the next-to-last chapter, which he begins by saying, "I didn't understand 'Watergate' until long after I had been fired in the spring of 1973."

The Ervin Committee heavy of the cocked eyebrow and the sneering belligerence is unrecognizable in these reminiscences of five years in the Nixon White House. Any history of that time in which Vietnam is but a footnote and Watergate almost an afterthought is the work of someone who has another ax to grind. None of the fevers of the tapes and the trials are registered in his noncommital -- and often spiteful -- account.

It says something about John Ehrlichman that he never mentions the fateful names of Woodward and Bernstein, the two young Washington Post reporters who gave Nixon his ultimate "historic first" -- that of being the first president to resign from office.

It tells you even more that he never tells you how he felt about Richard Nixon. He must be one of the few Americans alive who seems to have no views whatever about our most maddening president. Nixon often called Ehrlichman "Bob" -- as in Bob Haldeman. And he never learned how to spell Ehrlichman's last name. He also fired him and refused to testify at his trial. But Ehrlichman, curiously, seems to harbor no strong feelings about the man who was responsible for his years in prison. He exhibits far more passion against Dan Rather of CBS, whose "laziness" and vindictiveness he finds unpardonable.

Ehrlichman talks about Nixon the way a tenant farmer would discuss a moody squire. He offers no insights, displays no curiosity about why he did what he did. He recounts, without comment, Nixon's disjointed monologues, his outbursts, his indecisions. He tells us tolerantly about a famous "firing" breakfast with J. Edgar Hoover -- who got up from the table with a 20 percent increase in FBI overseas personnel.

The former domestic counselor explains that he had invested some time in Nixon's career and saw him as a ticket for a seat at the big power poker game. Or so he would have you think.

Deadpan, he recounts the funniest line in the book, which was uttered by Nixon after Ehrlichman, defending the president's failure to hold press conferences with his usual vehemence, accused the press of asking "fairly dumb and flabby questions."

Said Nixon, and it is him to the life: "Kicking the press is an art. Your flabby-and-dumb crack was good. You let them have it without rancor."

Ehrlichman may have thought that bitterness would smirch his canvas of a sensible, rational group of people who were immersed in clean air, clean water, government reorganization and revenue sharing -- and were blind-sided by an episode which they hardly noticed it until it was too late.

Ehrlichman doesn't tell us much about himself or his formidable sidekick, Haldeman, about whom he reveals an unexpected dryness: Haldeman sometimes referred to Nixon as "Thelma's husband."

The people about whom he tells us most are those he likes least. He strips the judicial robes off Warren Burger, showing us a panting, pompous careerist who chit-chatted about court cases at the White House.

He is merciless towards Henry Kissinger, whose conduct was so preposterous as to be hilarious, without ever explaining why no one ever took him up on his periodic threats to "return to Harvard at once." Kissinger's savagery toward Secretary of State William Rogers vexed Nixon, but he also regarded Rogers as "ineffectual, selfish and vain."

Ehrlichman reports, without irony, that once during the Paris peace talks, Nixon "wondered out loud if Henry needed psychiatric care."

He settles other scores. John Mitchell was an incompetent who "looked like a tapir." He agrees with Nixon's verdict on Mel Laird -- "a sneak." These nuggets are scattered through a relentless recital of bureaucratic battles over incomes policy, school desegregation and other "substantive" matters which consumed most of Ehrlichman's time.

Ehrlichman goes light on Chuck Colson, whom he suspected of much end-run mischief. In malice, bias, stupidity, naivete and general all-round worthlessness, he found no one in the White House who rivaled many members of Congress, most of the White House press corps and of course, the federal judges who presided at his trials.

Living at peace in New Mexico now, Ehrlichman has become convinced that "Nixon perpetrated the Fielding (Daniel Ellsberg's psychiatrist) break-in." But he doesn't hold it against him. His other grudges are much graver.