"I'm pretty sure I'm leaving, but I haven't told him yet," said Sen. Harrison A. Williams' chief aide. His name is Walter Ramsay, and he has been with Williams since 1969. Sen. Williams was trapped in Abscam, and is fighting a move to expel him from the Senate next month. But for Ramsay, there is also another fight.

At the moment, however, he is dining on veal piccata, and his companion on quail. They are old pals. Especially Ramsay, who is 46. He laughs, as in the good old days. Sure, he enjoys his job.

"I've got a top security clearance," he says.

"Yeah? What does a Senate aide need with that?"

"Beats me. When I first got it, I thought there would be a number you called every morning to get all the secrets."

Of course, he does not laugh quite as much nowadays. Williams' situation is not particularly funny, and neither is Ramsay's.

"If the tapes had been in color, with professional lighting, the jury would've never found him guilty," he quips.

Then adds seriously: "Really, the visual quality of the Abscam tapes is totally sinister. The scene itself is ingenuous, but it intentionally set a mood. It was run like a magic show. One hand distracts you, the other hand does the trick. The trick was to make Williams look like he did something wrong . . .

"I don't like leaving him, especially now," Ramsay adds. "I guess I'm doing it for Sean."

Sean is Ramsay's 21-year-old son. It's funny how life changes, Ramsay says.

On the evening of Feb. 2, 1980, he had gone to see the movie "Apocalypse Now" for the third time. ("It's a hell of a movie, that's all"). On the morning of Feb. 3, Abscam broke in the newspapers.

On Oct. 12, 1981, Sean was attending a homecoming weekend fraternity party at Kenyon, where he was a freshman. He fell or was pushed and hit his head on a table. There was no external injury, but the impact severed an artery of his brain and he went into a coma for 47 days. He is still recuperating, and has gained back some of the use of his limbs.

As a general characterization of the situation, Ramsay, how does "nightmare" sound?

"Sounds about right," he says, swilling his grapefruit juice. Ramsay drinks a lot of grapefruit juice these days.

A few weeks before the primary election of 1970, Williams discussed his drinking problem with a reporter from The New York Times. The Times reporter wrote a story which got good display. It revealed that the senator had been an alcoholic, but had quit some months before. Williams won the primary and was reelected by a landslide.

Ramsay was his press secretary at the time, a job he prepared for by getting a law degree at night from Seton Hall while working days as a reporter for the the Daily Journal (Elizabeth, N.J.). In those days, reporters and lawyers were, as a class, somewhat estranged, and Ramsay kept his night courses secret. When found out, he vowed "never to practice." It is a vow he has kept.

Socially, Ramsay kept his equilibrium. One winter night in 1967, after setting a house record in the category of martinis, he bid his host goodbye and walked calmly out the door into the freezing rain. After 20 minutes he returned equally calmly to announce, without a glance at his stockinged feet, "I appear to have forgotten my shoes."

Ramsay says he has no memory of any such incident. In 1975, however, he "decided to stop setting those kinds of records."

Good old days.

Ramsay shrugs.

It is suggested to him that many could not take what he is going through and smile, much less laugh.

"Well, I'm Irish, you know," he says unnecessarily. He often wears one of those crunchable tweedy hats, but lately he has learned to take it off in restaurants. "You think about what Moynihan said when John Kennedy was killed. There's no sense being Irish if you don't know that sooner or later the world is going to break your heart."

In fact, he says, it is Williams and Sean who keep him going.

"Williams is a tower of strength in all of this stuff. He carries us along with his spirit. There is a substantial amount of pressure, but you feel like you're doing the right thing. No, the atmosphere of the Senate hasn't changed toward us at all. I guess the people who have negative thoughts don't tell them to you. What you get is, 'Hey, boy, he's getting screwed.' There's probably more good feedback now than before.

"The same with Sean. If he's feeling okay, if he's joking, I feel okay. It's when he gets depressed that things are bad. But he's remarkable. He's lying there in the hospital watching TV and he says, 'Hey Dad, if you catch me watching Merv Griffin then you know the brain damage is terminal.' "

Ramsay sips the grapefruit juice. "I don't laugh as much as before, but I can still have fun. We have little parties at the office on somebody's birthday, like before. We joke around. I can go home at night and read a good book. I can still enjoy it. Boy, I must read about 10 books a week these days."

So the spirit survives.

"Well, with Williams, things are definitely improving," he says brightly. "Sen. Inouye is with us now. And Sean is making progress.

"It depends on how you're looking at it. If two objects fall off a building at the same time, then according to Einstein's theory they are falling at 32 feet per second per second, or whatever. They appear to be falling, but relative to each other, nothing has changed."

That's Einstein's theory?

He shrugs, grins.

"It's hard to describe," he goes on. "It has something to do with what Venturi said about architecture, about complexity and contradiction. He visited the Las Vegas strip, and found it terrifyingly complex and contradictory, but somehow, as a whole, still beautiful.

"You have to remember that both cases, Sean's and Williams', are very different from being an irrevocable tragedy. Such as death. Then it would be over. But in both of these situations you're intensely involved all the time. There are things that you can do, so you do them. That increases the stakes."

Ramsay plans to stay in Washington and continue to commute to New Jersey on weekends, where his wife, Betsy, teaches second grade.

"Washington is all right," he says. "But it's the capital of 'who're you with, whatta you do.' It doesn't get that personal. Everything's big and important, but the city's like a glacier. You don't even know it's moving until a big piece falls off and blocks the ship channels.

"You know where I'd like to live? Mansfield, Ohio. That's where they took Sean. It was the nearest hospital to Kenyon with good neurological facilities. Everyone there was incredibly friendly and concerned. They talked him through those 47 days, when nobody knew if he could hear you or not.

"It's a blue-collar town. But my father was a railroad engineer, and I could be happy there."

Reality has successfully inoculated him against paranoia, but there is still the matter of hate. After all, the Justice Department is trying to destroy his boss.

"Personally, I find it impossible to hate. I'm not against it, because it gives great energy. And many of the people we're up against you do feel a dislike for. Particularly those who set up Abscam. I mean Thomas Puccio and the Federal Strike Force in Brooklyn. But I feel I'm emotionally objective."

What view does emotional objectivity bring him to in this case?

"My emotional objectivity brings me to the view that Williams was framed and that that's totally wrong. I was thinking, in the hospital at Mansfield, waiting for Sean to wake up: Here is Williams, working a lifetime on health legislation to help people in situations like this, and there are these other guys, sitting around dreaming up ways to frame people."

Difficult times. He tries, but the gag doesn't come.

"Yeah, I've lost some of it," Ramsay says. "But not all of it. I used to sit around thinking up things to do. My wife said, you want something to do, go make a parachute jump. So I made a parachute jump, and came home clutching my little certificate. I told her and she said, 'Oh?' "

Ramsay does not look around for parachute jumps these days. There is much else to do, and some of it is difficult.

"If you can keep your sense of humor it helps everybody," Ramsay says.

"Williams has his, Sean has his. One night a couple of months ago Williams called me up at midnight. He had just seen the movie 'Arthur,' and he was recommending it. He was laughing. He thought it was pretty funny.

"The funny thing is, I had seen it myself that night. Sean and I had seen it together. Sure we laughed. We laughed our heads off. It's a comedy, right?"