Upstairs in the Terrace Theater, two sopranos were trying to steal the scene from a third.

Downstairs in the Eisenhower Theater rehearsal room, seven singlers were being whipped into shape to have a collective, on-stage identify crisis.

Backstage, Martin Feinstein, who hopes to fill the Terrace Theater 35 times between July 10 and Aug. 19 was brooding about OPEC.

"What if the gas shortage keep them away?" he mused.

"If only we could get the gasoline," Feinstein brooded. Then his expression brightened. "But if we go down, we'll go down in glory.

Feinstein's ambition, shared with the 120 people who have become the Kennedy Center Summer Opera, is as relatively modest one: to present new productions of four operas during July and August without losing more than $250,000. With a total budget of $550,000 [about half of what the Metropolitan has been known to spend on one production], they are looking on a low-budget miracle -- and a few days before opening night, were working hard to make the miracle happen.

Two operas [or three; it depends on how you count them] are in production simultaneously right now at the Kennedy Center. Two more will replace them at the end of July.

Downstairs in the rehearsal room William Dansby strides acorss an imaginary stage, turns to Elain Bonazzi, a signs to her a rich bass-baritone: "Who knows? You may be a puppet next." Bonazzi smiles back at him, quizzical but happy.

In Dominick Argento's opera, "postcard From, Morocco," Dansby is a puppet-maker who models his puppets on people. But at this stage of the production that will open next week at the Kennedy Center, all seven singers [and two mimes] are puppets. They learn their moves while the puppet master director Lou Galterior, dances on the sidelines, orchestrating their gestures with his own.

The rehersal room looks something like a small basketball court -- bare, white walls and open stretches of floor with mysterious lines taped across it to represent scenery. [one piece of masking tape is labeled "tree," any actor can walk around it, an imaginative one might hide behind it -- but only a genius could climb it.]

"Postcard" is not yet ready for costumes: Bonazzi is wearing white slacks and a blue-striped man's shirt Upstairs, on stage in the small, exquisite Terrace Theater, Mozart's "The Impresario" and Weber's "abu Hassan" [which also open next week] are more advanced, with scenery, props and a few costumes from the last century [Mozart and Weber have been transferred to Washington in the 1880s].

Soprano Janice Hall wears slacks but carries a ruffled parasol and sometimes wields it like a weapon. Director Jack O'Brien is polishing small details: How will the chrous spread itself across the stage?

At the podium conductor John Mauceri stands conducting the singers across an empty orechestra pit. A piano in the corner supplies the overture and accompaniments -- orchestral rehearsals are for later, but meanwhile the actors must get used to the conductor's style and practice watching him out of the corner of an eye.

The "Postcard" cast is intense, involved, working itself up to a taut psychodrama that demands unusual acting as well as singing ability. "In this piece," Galterio explains after one rehersal, "you can't hide behind the plot -- those seven artists have to make it work, and the only way they can do it is through their own personalities, their own experiences, their own fantasies.A lot of self-revelation has to happen, and with different performers it could be a very different opera."

The atmosphre backstage at "Impresario" is different -- more like a Broadway musical. Some members of the cast are straight actors with speaking roles, and the actors outnumber the five singers by two to one.

They are working on what amounts to a new play with old music, and there is some of the nervousness of a world premiere in the air. "Does it work? Is it funny? Do you think we can get it all together by opening night?" asks tenor Raymond Gibbs, going down in the elevator after a rehearsal.

"Impresario" and Abu Hassan," recast into a single piece of work by playwright Hugh Wheeler, may open a new niche in the dramatic spectrum, somewhere between Broadway and the opera house. [wheeler's previous credits include "Candide" with Leonard Bernstein, "A Little Night Music" and "Sweeney Todd" with Stephen Sondheim.]

Commissioned by the Kennedy Center to join the two pieces, Wheeler wrote a completely new script for the Mozart opera, keeping only Mozart's music and following the hints in that music that the plot should involve a conflict between sopranos.

Then for the second act, he retouched the Weber script more lightly, working in the soprano conflict to add another comic dimension to what is already a funny opera. "You know," Wheeler reflects, "I don't think of it as Weber's 'Abu Hassan' any more. Now it's my 'Abu Hassan.'"

It may also become a busy, new addition to the American operatic repertoire, although Wheeler prefers not to speculate on that.

He is happy with his latest musical collaborators and thinking of writing new scripts for some Viennese operatas whose music is still fresh while the plots have become outdated. "I love working with Steve Sondheim," says Wheeler, but Mozart never criticizes anything I do."

Both of the productions that open next week -- although they are strikingly different in other ways -- are part of an effort to enlarge the opera audience by bolstering the dramatic values in performance.

Benjamin Hendrickson, one of the nonsinging actors in "Impresario," said this was his first operatic experience and "I'm in awe of the singers, their techniques and discipline. An operatic production seems to happen a lot faster than plays come together -- they know what they're doing and it's fascinating to watch."

The singers are equally fascinated by their race chance to work closely with actors. Janice Hall, who plays a very temperamental Italian soprano, recalls that she was interested in theater before becoming a singer and finds it "wonderful to get back into doing dialogue." Faith Escham, who plays one of her rivals onstage but is a friend offstage, finds it "a kind of experience opera singers don't often get -- like having acting lessons every day."

Elaine bonazzi finds the intimacy of the Terrace Theater, which has about 450 seats when the orchestra pit is in use, "like performing on television -- always in close-up" and believes that "Postcard From Morocco" is "a masterpiece."

The general enthusiasm of both casts -- some of whom bypassed higher-paying assignments elsewhere to sing here -- was summed up by William Dansby and echoed by several others: "There's nothing quite like this happening anywhere else in this country. A lot of us are here because we want to see American opera going in this direction." CAPTION: Picture 1, Janice Hall in rehearsal for "Impresario," by Harry Naltchayan; Picture 2, Rehearsal for "Impresario": Two operas [or three; it depends on how you count them] are in production simultaneously right now at the Kennedy Center." Photo By Harry Naltchyan -- The Washington Post