Joseph Papp doesn't dash into the breech periodically. He N dwells there. On this particular Manhattan morning--with the sky hanging low, like a dingy washcloth--he is racing uptown for a hastily scheduled meeting to save the Morosco and Helen Hayes theatres from the wrecker's ball. Smoking a fat cigar, he is sitting in the front seat of the Jeep station wagon that serves as the limousine for the Public Theatre. But he gives the distinct impression he is riding shotgun through Indian territory.

Founder of the free Shakespeare in the Park, indefatigable director of the Public Theatre for 15 seasons, spiritual godfather to a generation of American playwrights and producer of such Broadway bonanzas as "A Chorus Line" and "The Pirates of Penzance" (which opens tomorrow at the National Theatre), Papp is digging his heels in again.

It's a real cliffhanger, this last-ditch effort to save two venerable Broadway theaters from going the way of all dust, and Papp's adrenalin is pumping furiously. Atlanta super-developer John Portman stands poised, ready to begin construction on a 50-story hotel on the very patch of land occupied by the landmark theaters. A few days later, the New York Court of Appeals will handdown a ruling paving the way for demolition. In the meantime, Papp has thrown his weight on the side of the theaters. As the Jeep threads recklessly through the midtown traffic, he can think of nothing else.

"All weekend I debated with myself whether I should fight to get rid of this hotel. It's a monstrosity that doesn't belong on that street. But I decided that was too radical. What I want to do is convince people that you can build over those two theaters. And you can. The point is if you fight this in offices and over the telephones, it's deadsville. I say keep the street scene alive. Keep the drum beat going. Let people know you're alive."

He's got calls out to Mayor Koch, the Shuberts, even Portman himself, a formidable array of opponents even for one as feisty as Joseph Papp. What's foremost in his mind, however, is the drama he wants to stage in front of the Morosco--performers reading excerpts from works ("Abie's Irish Rose," "A Touch of the Poet," "Arsenic and Old Lace") that played there; a shower of 150,000 leaflets urging theatergoers to "Save the Theaters"; a 50-man honor guard round-the-clock to prevent the wreckers from doing their work in the dead of night. And if all else fails, he, Joseph Papp, is willing to lie down in front of the bulldozers.

The Jeep rounds a corner and heads down 45th Street.

"Look at that. It's going to be ghastly down there," he sighs. "This is the most beautiful street, this 45th Street. How they'd love to get their hands on the Morosco! It's a great theater. Hell, I could fix it up for a million bucks. Be a first-class theater."

He instructs the chauffeur to pull the Jeep into Shubert Alley, the pedestrian mall between 44th and 45th streets and the spiritual heart of Broadway. "They don't like me to park in this area, even though I have a hit here" (he gestures to the Minskoff Theatre, which houses his pop version of "The Pirates of Penzance"), "and a hit here" (grander gesture to the Shubert Theatre, where "A Chorus Line" is still kicking strong in its seventh season). "I'm conducting this whole radical campaign from Shubert territory," he laughs. "There are ironies in all this."

The following morning, Papp is ensconced behind his vast desk at the Public Theatre in the East Village, rather like a field marshal in the thick of battle, shooting off memos, answering phone calls signaled by a sharp buzzer, scheduling meetings at which he will invariably arrive a few minutes late. Large feathery snowflakes, winter's last gasp, are drifting down outside the massive stone edifice, a public library before Papp decided to make it a beehive for the arts.

"What this whole Portman thing is f------ up is my work on plays at the Public. I've taken away a lot of people from their jobs here to help with the demonstrations. Now I'm getting complaints. All the energy I'm putting into this fight, I should be putting into the theater itself," he says. "Back in the 1960s and '70s, a lot of plays we were doing were related to the social conditions and forces at work. We were doing plays about Vietnam, about civil rights, about the black situation. There was a tremendous amount of ferment. The biggest ferment we've had recently is this Portman battle."

A bzzzzzzzzz cuts him off. Papp snatches up the phone and finds himself pacifying a jittery hostess, who has agreed to help him promote Bonds for Israel.

"If the times were ripe," he says after the phone call, with no sense of interruption, "I'd be producing fantastic plays dealing with the nuclear problem, with war and survival. A few hard-hitting plays are starting to come in now, but you can't generate that stuff by yourself. The theater is no different from the rest of the world. It reflects the world, and the mood is very conservative now. There's no question the country has seen a diminution of the kind of energy a place like this draws on. Because we're a social theater. Even when we do classics, we go out into the streets with them. That's a social statement, too."

Bzzzzzzzzzzz. "Yes, Detective . . . I see . . . I appreciate that. Thank you, Detective."

He hangs up the phone as if nothing were unusual, and draws a quick breath. "The reason I'm so goddamned caught up in this Portman campaign is because the theater today is not satisfying me in terms of what it's doing. And when the theater gets less of life than what is on the outside, I've got to be out there doing something."

Bzzzzzzz . . .

At 60, Papp is a celebrity in his own right, a flamboyant showman who was recently tapped by United Airlines to be a spokesman in one of its television commercials. ("Listen, Olivier did commercials," snaps Papp, who used the occasion to plug "Pirates" and then put his fee into the Public Theatre's coffers.) A consummate publicity-getter, he knows that fully half of the art of successful ballyhoo is confrontation. And vice versa. He once appeared in his own one-man cabaret show in a SoHo restaurant, singing pop tunes and talking about his impoverished Jewish childhood. While he says it was "the most nervous time of my life, I'll never do it again," the greasepaint still courses in his veins. Regularly, he tapes radio commercials, in which he sings "Hava Nagila," instructs people to "do the Joe Papp tap" down to the Public Theatre and quips, "If you don't like my tap dancing, I also play the violin."

Such antics have a purpose, besides tickling Joe Papp's sizable ego. They help keep the Public Theatre, perhaps the most influential theater in America today, visible and solvent. Their opposing stances on the Portman issue notwithstanding, Bernard Jacobs, president of the Shubert Organization, calls Papp "one of those who has had the greatest positive impact on the theater of his generation, even if he is a big pain in the a-- sometimes."

Papp's dedication to emerging playwrights is legendary, although he sniffs at the notion of a "stable" of writers. "Only Jesus Christ had a stable," he barks. "I have a number of playwrights and directors I've put on the payroll. They get medical benefits and everything. It's to try to keep them stable, so they don't fall apart. So they can write." The list of those who have benefited from his largesse includes Ntozake Shange, Jason Miller, Miguel Pinero, Charles Gordone, David Rabe, Thomas Babe, Elizabeth Swados, Sam Shepard and David HenryWang. In short, the cutting edge of contemporary playwriting.

The big Broadway blockbusters have a function, however. Without them, the Public Theatre would be greatly diminished in scope. To date, "A Chorus Line" has returned $12 million on a worldwide gross of $34 million to the Public Theatre, and "Pirates," which is soon to be a movie under Papp's aegis, has contributed a profit of $1.5 million. The figures are deceiving, though. "Some people now think we're a big money-making machine," Papp says. "But 99 percent of what we do is noncommercial. There are 350 people on the payroll and it costs us $7 million a year just to run this operation. If we have two or three flop shows, we could be out of business. Fortunately, 'A Chorus Line' has been maintaining us. But it's a helluva way to live. A theater this size needs an endowment of roughly $75-100 million to get through the lean years." (At present, the endowment hovers around $12 million.)

Papp does not count on the Reagan administration for much help, if any, although during its Washington run, the "Pirates" cast, backed by the Marine Band, will be performing excerpts from the show at the White House. "Of course, I hate what's happening, and not just in the arts area. We're very concerned about all cuts--in school lunches, in medical care," he says. "Theaters are humanistic institutions by their very nature."

The drift of foreign policy also worries him. "Whenever there are encroachments on another country's freedom, you have a danger to rights in this country. I'm very sensitive to that, because theaters are also places for free expression. The climate that's being created, well, it's not as bad as it was under Nixon, but it's like a cloud that's getting larger. Sure, my first impulse is to say, no, we won't perform at the White House. Why should I after all these cuts? But I don't want to be a turned-off person. I want to have a talking relationship with the president. Maybe I can get his ear. Maybe I can get a word in."

So Papp forges ahead, refusing to believe he will not eventually prevail. Occasionally, he signs off on the telephone by saying "Excelsior" ("Ever Upward.") It could be his motto. Currently, he is negotiating with the ABC cable network, ARTS, to produce a weekly program, sort of an intellectual "Ed Sullivan Show," called "The Lost Art of Conversation Variety Show." It would mix discussions by "interesting people on current topics of concern," with segments devoted to a Spanish punk band, an Irish tenor, a 10-minute opera by John Guare, an investigation of the sexual life of the mite and theatrical reviews from "the child critic," a 9-year-old boy Papp finds particularly lucid. Papp plans to be one of the cohosts and may sing a little.

He's just engineered an exchange program between the Public and the prestigious Royal Court Theatre in London, which will swap eight English actors for eight American actors. He is overseeing $800,000 worth of renovations on the Public's facilities. And he plans to get the long-stalled movie version of "A Chorus Line" under way shortly by producing it himself.

The schedule would tax a man half his age, but one suspects that Papp's fast pace simply begets an even faster pace. "Hell, if I took the long-range view, I wouldn't get out of bed in the morning," he shrugs. "So I take it issue by issue. I win some, I lose some. There are times I lose too many, then I'm no good for a couple of weeks. Oh, I keep working, but I'm drawing on reserve energy, on the energy of those around me. I suppose I'm tough on certain issues. But I can be knocked over with a feather. Like this television critic who takes a swing at me out of nowhere. He doesn't like my radio spots. 'Embarrassing singing commercials' was the phrase he used. What's embarrassing? The only reason I do it is to bring attention to this place. The other day, I got a lovely letter from someone, saying how much he liked those commercials. A very sensitive person, naturally. Let me show it to you."

But Papp doesn't have time.

Bzzzzzzzzzzz. His secretary reminds him of an imminent appointment. Back into the Jeep. Back uptown to save the theaters. Papp snatches a piece of sheet music on his desk. "I gotta learn this song for some damn show I'm going to be in to help raise money for a dance company," he explains. "Then I'm supposed to do a tap routine!"

Trailing his raincoat, he flies out the door and in a raspy baritone starts belting out the lyrics, "The song is ended, but the melody lingers on, the melody lingers on . . . the melody lingers on."

"Melody, Joe, or malady?" calls out someone in the hall.

"Melody and malady," retorts Papp, off to wrestle the dragons.