A spotlight comes up on stage. A dispirited Richard M. Nixon is alone in the Oval Office, packing up a few belongings in a cardboard box before relinquishing once and for all his grip on the presidency.

The 20-piece orchestra swells. Nixon sings:

Where do I go from here

When I walk out that door

And hear those gray and grinding voices

Whisper "Never more?"

What will I say to those,

The ones who will not grieve,

Shall I insist that there are some,

Who still believe?

The orchestra is building in intensity, a low murmur of timpani adding to the drama of violins taking flight. Nixon sings on:

What will they think of me

And what will hist'ry say?

A clever fool who fooled himself

And somehow lost his way?

I tried for all of it.

If I lied a bit,

And it's time to pay my dues,

At least give me this:

I cared enough to lose.

Watergate as a musical? The idea alone sounds utterly preposterous, something that Mel Brooks might cook up as a topper for "Springtime for Hitler." But hold on a minute. You could have Rose Mary Woods chirp "All I Did Was Push a Little Button." What better running gag than Martha Mitchell's expletives? Mo and John Dean could have a lush, heart-wracked duet. Pat Nixon could sob, "There are just too many demands . . . too many outstretched hands," and in a number called, say, "Can't We Keep It Simple?," plead poignantly with her husband to save a little time for them.

To launch act two, folksy Sam Ervin could bound on for a hoedown about the only three things he trusts, "God, Country and Caroline"--Caroline being, of course, his beloved state of North Carolina--and it wouldn't hurt to have him kick up his heels the way they do in "The Best Little Whorehouse in Texas." Maybe some of the Watergate burglars could do "The Wiretap Blues," a tap dance, silhouetted against the D.C. jail--sort of like "Too Darn Hot" in "Kiss Me Kate," only more topical. And what if--oh just what if--Nixon admitted he'd always wanted to be in show biz? Better still, that he'd always dreamed of teaming up with Groucho Marx! Can't you see it? Straw hat, cane, sandpaper shuffle. The man they said you'd never buy a used car from actually going out on the stage and selling 'em a soft-shoe.

The intermission could even be 18 1/2 minutes.

WELL, READY or not, Broadway, here it is: the summation of 10 years of headlines and melodrama, anguish, soul-searching and inadvertent comedy--Watergate as a musical, clearly labeled, so as not to confuse the dimwitted, "Watergate, a Musical." Currently tucked away through the end of the month at the Alliance Theatre here, the $500,000 production stars Gene Barry, once Bat Masterson himself, as Richard Nixon, and a supporting cast of 22, mostly Atlantans, as everyone else. The authors, two middle-aged West Coast writers, Tommy Oliver and Ed Lakso, say they chose Atlanta as their tryout city because "it's a progressive town," and "when you come from L.A. and the film community, the theater world is a rather closed one." But later they'll admit, "We really came down here to hide out from the critics."

Not that the local critics were kind. Scott Cain of the Atlanta Journal found it "a humdrum musical . . . dwarfed by its subject." In the Atlanta Constitution, Helen C. Smith observed justly that the show simply has no point of view and that "though it has some good scenes, several tuneful songs, and a handful of fine performances--and enjoyed a standing ovation--it lacks theatrical suspense."

Buoyed, however, by the genteel blue-haired ladies and their soft-spoken mates, who do, in fact, rise regularly to their feet at the curtain call, the producers promptly took out a $2,500 half-page ad in the Atlanta Constitution trumpeting the "Tuneful songs . . . fine performances . . . a standing ovation" and thanking Atlantans for their warm hearts.

Now, according to Oliver, "Plan A is to go to New York."

"As soon as I can get off my can and do some rewrites," adds Lakso.

In the euphoria, born of the moment, there really doesn't seem to be a Plan B. "We're going to die with this thing, one way or another," says Oliver.

THERE MAY be a fitful tradition in the theater of corrosive political satire--"MacBird," which took apart Lyndon Johnson, or the Atlanta-hatched "Red, White and Maddox," which dismembered Lester Maddox. "Watergate, a Musical" is certainly not one of them.

"What we specifically didn't want to do was a spoof," explains Oliver, who produced Vicki Carr's "It Must Be Him" album, and has done the arrangements and conducting for such TV fare as "The Donny and Marie Show" and "The New Laugh-In." "Nixon doesn't deserve that. We really should forgive and get on with it. The idea was neither to vilify nor exonerate, but to make a statement about this country, this fabulous country of ours, that in a time of crisis turns from malted meal to a very dense piece of metal. Do I sound like a flag-waver? Because I am."

Although Oliver claims he researched the subject for months, he was stymied by the problems of musicalizing Watergate, until Lakso came up with the brainstorm that unleashed the full might of their creativity: the character of Benjamin F. Watson. As played by John Steele, a young Denver actor who looks a little like Alfred E. Neuman and sounds like Andrea McArdle before her voice changed, Benjamin is a precocious 12-year-old who detaches himself from a tour of the White House, wanders into the Oval Office and asks Nixon point-blank, "How did it happen? . . . How did it come to what it's come to?"

The musical, apparently, just fell in place after that. Oliver and Lakso churned it out in six weeks' time, a collaboration that was complicated only by Lakso's habit of writing in the Skytrails Restaurant of the Van Nuys Airport. "Yeah, I can't stand to write alone," says Lakso, who has given the world episodes of "Flipper," "Starsky and Hutch" and "Charlie's Angels." "I always go to a crowded room. There's one booth I went to for 11 years."

Although the authors stress that their musical is based strictly on public records and accounts, they took out libel insurance--just in case--and had a Los Angeles law firm scrutinize the script. "It's hard to libel a politician," says Oliver, "but our original portrayal of Mo Dean was not too kind. We had daily battles with the attorneys."

"Be careful, Jesus," warns Lakso. "Tommy and I still argue over John Dean. Nothing major."

"Yes, it is," says Oliver. "It's my feeling John Dean was not the patriot he is in our show."

"And I don't think I've written a patriot," counters Lakso. "That's the argument. I think I've portrayed him as a weak, frightened man who fell back on a moral posture that no one could argue with, just to save his hide."

"Well, if that's what's coming through . . ." says Oliver, calling a truce.

What unites them is the suggestion that maybe they have painted Nixon in overly sympathetic colors.

"If saying that a man lied, cheated and schemed is being sympathetic!" bristles Lakso. "That's a recurring line in the show."

"But in our minds that's not unique to him," says Oliver. "That's 80 percent of the business world, as well. That's the guy who doesn't pay 50 cents at the toll booth because he figures he can drive away fast enough before someone catches him. What we hope to do is help people understand it isn't okay to lie and cheat. Look, we're not trying to drive a nail in Nixon's coffin. But this is no whitewash, either. If you're a staunch anti-Nixon man, maybe you'll have some compassion for him. If you're pro-Nixon, you'll probably come away still pro-Nixon. We're not out to change anyone's mind. We're celebrating the country. Our ultimate salvation is that the office of the president and the city of Washington are still there."

Nonetheless, a benevolent Nixon who, for 2 1/2 hours, sips milk, nibbles cookies and talks Watergate with a bright kid from the heartland? A gruffly good-natured Nixon who calls Rose Mary Woods "a great broad" and treats her the way Don Porter used to treat Ann Southern on "Private Secretary"? A singing/dancing Nixon imagining what it might have been like to do a vaudeville number with Groucho?

"Everyone likes that number, but can't find a reason for it. I'll tell you where it comes from," says Oliver. "I met Nixon once, when I was conducting at a White House party for Prince Charles and Princess Anne. Nixon came out on the White House lawn, and we were chatting. It was very uneasy. I was in awe. To make conversation, he said, 'I envy you. I always wanted to be in show business.' I later learned that when he was courting Pat, she was doing community theater. The two things together seemed to justify the number. Of course, he never actually said he wanted to team up with Groucho. That's musical comedy license."

He smiles a broad West Coast smile. "Anyway, this show is mainly entertainment, with a lesson underneath. Even if you don't understand the politics, you can go out humming the songs."

For opening night of "Watergate, a Musical," the Georgia Democratic Party bought up rows of seats for a benefit, resold them at $75 apiece and then settled in for some good partisan fun. "I think they laughed a lot less than they expected to," says the PR man for the Alliance Theatre.

SMALL IRONIES department: The actor who plays John Ehrlichman--a walk-on, really--doubles as a street peddler in the big musical tribute to D.C., "Uncle Sam's Company Town." The actor playing Henry Kissinger also plays a street cleaner. Ed Herlihy, who plays Sen. Sam Ervin, has been for 35 years the voice of Kraft cheese on radio and TV. Herlihy paid $40 for a pair of bushy eyebrows, specially made for the character, but he admits he has trouble getting them to move up and down.

GENE BARRY carries a heavy load on his shoulders. He eases into a Formica chair in the greenroom of the Alliance Theatre, and then announces in stentorian tones, "The responsibility has fallen on me to play the most known person of our times, who's still alive, who has marked our memories and our lives. Think of it! It would be easier to do George Washington, although I might have trouble with the teeth."

For a while, however, it seems that Barry was having trouble with Nixon's hair. A hairpiece accentuating the creeping baldness that Barry feels is the key to the Nixon look kept moving around in performance. Now, the actor waxes two triangular-shaped wedges an inch and a half into his own full head of hair, and applies flesh-colored make-up to the wax. Then he goes after the jowls. The press releases say he spends two hours getting ready, but Barry shrugs that off. What's really hard, he suggests, is playing a man who "politically and emotionally has two left feet," who's "uncomfortable," who'd be "a strain on a foursome of golf."

"Of course, I've played men of power before, but it was on TV. TV's more simplistic. When you become a motion picture star or a TV star, you play a copy of a copy of a thing you once created. I had three series--'Bat Masterson,' 'Burke's Law' and 'The Name of the Game.' Each time, they'd want to see me dressed up--with the girls, the style, the power. Each time I'd say to my agent, 'Can't you get me a part of a vulnerable human being?' I was operating on 20 percent of the spectrum. But with this musical, we're up in the 80th percentile. Afterwards, there's always 'King Lear.' "

At 60, Barry is well-preserved, affable and, although his erstwhile confidence doesn't betray it, on the far side of stardom. He says he's writing his autobiography these days, and one of the prospective titles for it is "The Golden Rut," his term for the lucrative but artistically limiting years in Hollywood that made him a household face during the 1950s. Four years ago, he was headed for Broadway in another musical, "Spotlight," as an aging song-and-dance man, who looks back over his career. The show folded in Washington. He's toured since with his wife, Betty (who plays Pat Nixon in "Watergate"), in lesser revivals of "Fiddler on the Roof" and "The Fourposter."

Now he talks about "the frustrations I've gone through all my life. My friends all know how important it is for me to come back to New York professionally. I grew up in New York. I studied opera there as a young actor. I played musicals in New York. I met my wife in New York. We had our first child in the theater. I hate hamburger to this day because that's all we ate then. So, you see, I've been there. I don't need the dough, but what a cycle complete it would be for me to go back starring in a successful musical. I want that more than anything."

Most of the people connected with "Watergate, a Musical" are reluctant to express anything but the limpest of political opinions. For example, Kay Daphne, the Florida actress who plays Martha Mitchell, admits vaguely to the "mixed feelings" that Nixon inspired in her, but adds she got married the year of Watergate and so "I was a little distracted. My mind was on happier things."

Barry, however, campaigned for Hubert Humphrey, "a close pal," was with Robert Kennedy the night he was assassinated and in 1960 actually considered running for the U.S. Senate against George Murphy. "I didn't agree with Nixon's policies or the way he operated. I didn't like his destructiveness in campaigning. I can't condone the man. But, as an actor, I can't editorialize on him. I don't dare. I have to play what the play says. He can't be an SOB all the way through. Audiences have to have some empathy for the man. Every one of us has some good feelings about ourselves. What I'm trying to find are the things Nixon likes about himself. It's totally challenging."

A few minutes later, a worried look crosses his brow. He leans across the Formica table. "We are letting him off the hook too easily when I say, 'If I lied or momentarily failed to keep the faith, if I hurt or bruised someone's sense of morality, legality or logic--I did it for a good reason.' You know what my subtext is at that point? 'I was saving my ---.' That was Nixon's good reason--saving his ---."

MORE SMALL ironies: The authors left out any mention of Woodward and Bernstein because, among other reasons, they were hard names to rhyme. Despite her belief that it's a "great honor" to play Martha Mitchell, Daphne told the producers she'd be willing to dye her hair honey-blond only "if the show goes to Broadway."

WHICH LEAVES the big question. Is the world at large ready for "Watergate, a Musical"? Before it opened, the show generated national attention on the "Today" show, National Public Radio and "CBS Morning News," largely for its curiosity value. For the out-of-the-way Alliance Theatre Group, which tends to be one of the country's lesser known regional theaters, the musical has been a publicity boon. Like most of the cast, Ed Herlihy is "eternally optimistic" and believes the day soon will come when "Nixon himself will be watching us."

Oliver, however, confesses that "Watergate" was submitted to the Kennedy Center, which replied "it wouldn't touch it with a 20-foot pole." And none of the crack Broadway producers has jumped in yet. Both authors admit that, eager as they are for the glow of bright lights, the big-time critics could just slaughter them. With the manic-depressive duality that tends to be characteristic of the theater as a whole, they act as if they've got a blockbuster on their hands at the same time they are panting for the slightest reassurance. Still, even for those who may pooh-pooh the musical as perfectly misguided, there is the puzzling matter of Georgia audiences invariably rising to their feet at the end of each night's performance.

"Yes, I most certainly stood up," explains one sweetly scented matron, as she makes her way up the aisle and out into the muggy night. "I always liked Nixon. Oh, I didn't like his clothes. But I liked him!"