The new John Ehrlichman, not that that's how he regards himself, appeared this week in the capital to promote his new novel, "The Whole Truth," whose excited publisher has gone into rather a lather about it.

Sensational revelations about the realities of presidential politics," and similar pap are claimed, but Ehrlichman himself is at least as interesting as his book.

Since his conviction in the Watergate coverup and his 18 - month jail term for it, he has become what one wag called "America's favorite mellowed - out Watergate criminal."

Ehrlichman's brown eyes have a soft look now, and there is nothing of the electric - charge movement one used to notice. His shoes are short boots that might have come from a shepherd in Arcady, and he wears soft, thick wooly socks and ignores the six inches of Ehrlichman shank that shows between his trousers and his boots.

At 54, his beard is full, with a few silver hairs, and his whole appearance and air suggest a fellow who is about to go outside and grill a steak while his wife mixes up a salad.

By some he is remembered as the Nixon intimate with a sense of humour and some sense of proportion, but others remember him as the arrogant Prussian, prone to lecture and correct, a pompous prig.

Whatever he was, he has been through hell and has emerged apparently in contentment and peace, cultivating (as Voltaire so strongly recommended, not that he did it himself) his garden.

I think geraniums in boxes on top of the wall would be great," he said, having read of it somewhere, and went on to say he has an old adobe house in Santa Fe (where he lived for nearly two years before going to prison) with two courtyards enclosed by adobe walls.

He was asked if he had a tile fountain, etc.

The pressure's on for me to get a tiled fountain but I haven't got one yet."

Somehow this did not seem like conversations with Ehrlichman a few years back.

He was asked if it's true, as one may read in some accounts, that he feels no guilt over Watergate or compunction for the past.The question itself is almost obscene, at if one enjoyed endlessly drooling over break-ins of psychiatrist's files and gloating over those who went to prison. It is a relief to hear Ehrlichman say:

"that's not exactly it. One of the advantages of having gone to jail is that now that's behind me. I made mistakes, and if I were living that time again, there are certainly many things I would do differently.

"But what's the good of that?" and his arms swung out in a gesture of pointlessness. "I have to play the game from where the ball is now."

"For a long time it didn't really register," he said. "I thought I'd escape jail. Then, when it became clear I probably would have to go, that was the low point.

"One of the good things was from a former inmate of the [minimum-security] prison who got in touch and wondered if I had any questions. Did I! He and his wife took me to lunch and answered a thousand questions about the day-to-day routine, and it made jail less of an unknown.

"I did't know if I'd be able to write letters, for instance.

"I'm not saying jail is just great, but it wasn't terrible either. No, I was never physically abused. I found it like the Army, lots of senseless orders and a sourt of countinuing coverup."

It was suggested that prisoners were not in the strongest position to complain of infringements of regulations by prison management, and he said that was indeed true.

"Prisoners are supposed to have a minimum of personal space, so many square feet. But the truth is they need a lot of labor for the prison glove factory, and if the factory turns out a good quota that's good for the jail, so they pack Mexicans and guys in to work the factory.

He was able to write his 1976 novel, "The Company," before entering jail, and to writemost of "The Whole Truth" in jail, which he left a year ago.

Some thought "The Company" was a thinly veiled portrait of Richard Helms, the Central Intelligence Agency chief at the time, and that he was made to seem the bad guy of the business.

But Ehrlichman, who had originally complained that his name was being "exploited" in the book deal, said it was a novel, after all, not a history - that he was not pointing the finger at Helms; and certainly the fictional portrait of the CIA chief's wife had nothing to do with Helms' wife.

In either of his books, he indicated, attempts to say, "Ah, here is so-and-so" will simply mislead the reader factually.

It's not too suprising, perhaps, that readers think a fictional CIA chief, in a book by one of Nixon's closest and most influential advisers, is the historical figure, and it may be disingenous of Ehrlichman to let his publishers capitalize on his inside knowledge while he also claims the fiction writer's immemorial right to fantasy and imagination.

He was asked if he felt, as some of the Nixon circle did, that Nixon dumped his problems on his associates and tried to make them fall guys to save the presidential hide.

"I see it this way. I had a professional relationship with Nixon for a time. Now there is no relationship at all; I haven't talked with him or seen him.

"But I don't feel bitterness or resentment."

There is nothing new in the wheel of fortune, by which kings are reduced to prisoners and the meek (once they get the knack of it) are exalted.

In the theater, a king in chains may reflect on his former state as a happy dream, but there must be others who think of their former state as a nightmare. Ehrilchman's reticence about Nixon does not suggest he regrets very much the trappings of Washington power.

He will not comment on the role of Watergate in his divorce from his first wife (with whom he had five children), but his present marriage and content certainly are at a pole from the days in which the power of the world was often touched or shaped by him, when he infuriated the Watergate committee with his taciturn belligerence.

For instance, when questioned about the White House investigations into the sexual and domestic habits of its political opponents, Ehrlichman said he knew of congressmen who "totter onto the floor in a condition of at least partial inebriation which would preclude them from making any sort of judgment on the issues that confront this country." If that could only be brought out through their political opponents, then the opponent "has an affirmative obligation to bring that forward," he said.

Outside his hotel the streets were alive with the young protesting nuclear power. It must have reminded him of other protests outside another White House.

Humor may not be the word for Ehrlichman so much as an easy calm. Rabealais noted the liberating results of a contempt for fortune which no man, after all, can force to his own desire, least of all rulers.

So that part of his life is over and he now intends to live in New Mexico in the adobe courtyards of his $89,000 compound and write - if not forever at least as far into the future as he can see.

He works until noon or 1 every day, othewise nothing would ever get written. He works on the speeches he will give on the lecture circuit, tapes five one-minute radio commentaries for Mutual Broadcasting, and makes a stab at magazine journalism.

"Unfortunately I had an article for Esquire," he said, meaning that he was not paid because it had been argeed with Clay Felker, the departed Esquire chief. So his article on Mexcian illegal aliens is looking for another home.

He also proposes to write a "memoir" on his Nixon years in book form.

There is no way he can escape references to Watergate - especially on the lecture trips - but he was asked what he would like to talk about his multi-city tour promoting the book, if he could manage it all his way.

"Invisibility," he said. "there are invisible things and people in America.The Indians. Prison. Illegal aliens. These are the sorts of things nobody wants to think about and nobody does, unless there is some crisis."

Ehrlichman had wanted to think about them in 1974, after his second Watergate convictions in the coverup trial, When he proposed to do "alternative service" to jail by providing legal counseling to the Pueblo tribes around Sante Fe. The former specialist in zoning law flew to New Mexico in early 1975 to meet with tribal leaders. Although judges John Sirica and Gerhard Gesell would not accept the idea, it is still much on his mind.

"They are sleeping dogs, and the White House has always had a tremendous sleeping-dog list of things that may not be well but that don't have to be tended to today.

"So you have with the Indians this revolving door or cyclical thing - somebody will say an Indian should be assistant secretary of Interior, then after a while it's thought Interior should have a man who gives full attention to the Indians, so you have a commissioner, and it goes round like that.

"You send a man out from Washington to deal with the Hopis or some tribe populous enough to be a real people, and he says Washington wants to negotiate their problems. Fine. But they tell him they have no treaty with the United States and maybe someday they will negotiate but not now. And the guy from Washington thinks they are all flakes out there."

Also invisible, he says, are illegal alliens from Mexico, many of whom he interviewed in jail.

"Usually they round them up and put them in a bus and ship them back to Mexico, so I was interested why these were in jail. There was no real reson that I could see - it seemed to depend on how much time there was in the attorney general's office as to how many were arrested."

These problems seem a continent away from the Hyatt Regency, where in the adjoining room Ehrlichman's wife of six months is sleeping. Ehrlichman met Christy McLaurine, 30, a former interior decorator with a 4-year-old son, on a furniture-shopping expedition in New York, and in less than a year they were married.

Ehrlichman is thinking of getting some sleep himself as his vistor leaves. But he is not impatient, and you gateher that you can stay as long as you like.

Some may find themselves wondering how a nice guy like Ehrlichman ever was John Ehrlichman at the White House, and some would say he was always better than the press made him out.

This time, in any case, he did not compalin about the yellow journalism of a reporter's paper, as he once did, delivering a righteous homily. He says he subcribes to the Washington paper he once had no special affection for - possibly still doesn't - and likes the garden column.

It is certainly hard to dislike him in person.

But he has substantial symbolic value still, for many people, for what they call corruption at the higest levels, and many think of him in connection with an imperial executive branch swollen with power and self importance, careless of laws that are inconvenient.

He has heard people hiss.

But he said he does not expect people to be hostile and inflamed when they meet him, and they are not.

"I get anonymous phone calls and letters," he said, and they really let him have it. "I like to think," he said without relish or rancor, "maybe I'm part of their therapy." CAPTION: Picture, John Ehrlichman: "I have to play the game from where the ball is now"; by Linda Wheeler*