Robert De Niro and Meryl Streep will be doing Chekhov at the Kennedy Center next year if an ambitious repertory program outlined by New York producer Joseph Papp yesterday comes to fruition.

Papp said he expects to bring his long-planned and star-studded reportory company to the Eisenhower Theater in the spring of 1981, performing three classic plays in rotation. De Niro, Streep, Jill Clayburgh and Paul Julia have already agreed to devote six months to the company, according to Papp. He is seeking commitments from Al Pacino, Jon Voight, Dustin Hoffman and Martin Sheen as well, he said.

Kennedy Center chairman Roger L. Stevens could not be reached for comment yesterday, but Center officials are known to be very interested in the Papp plan and anxious for details on financing, plays and stars before making a firm commitment. The only definite title Papp has revealed so far is Chekhov's "The Three Sisters" with Streep (as Masha) and De Niro (as Vershinin).

When orginally outlined by Papp and Stevens last summer, the repertory company was to be a joint project dividing its time equally between New York and Washington. The current plan calls for three months of rehearsals in New York, approximately two months of performances at Papp's Public Theater complex in lower Manhattan, and a five- or six-week visit to the Eisenhower Theater here.

Papp now estimates a total deficit of $1.5 million or more on the whole project and losses of at least $120,000 during a five-week engagement in Washington -- "even if it does very well," he said. The Kennedy Center, while no longer intending to raise money for the venture as a whole, would at least help cover the Washington losses.

Repertory -- the idea of doing an assortment of plays on alternating nights with the same basic company of actors -- is an expensive concept. It involves putting actors on full salary for a period of months during which they will be performing only a fraction of the time. It also involves elaborate and frequent changes of costumes and scenery.

Both the Kennedy Center and Arena Stage, locally, have considered repertory plans in the past but found them impractical. But Papp said yesterday that he was determined to go ahead with his new company, using "whatever resources we have." So far, he said, he has no definite commitments of financial support from corporations, foundations or government agencies.