Nicaraguan President Daniel Ortega said yesterday that indirect cease-fire talks with U.S.-supported contras should begin here immediately through the offices of Nicaraguan Cardinal Miguel Obando y Bravo, and Ortega added that he will announce today a plan for negotiations that might include a role for House Speaker Jim Wright (D-Tex.).

"I think {Friday} would be a good time to start it," Ortega said in a meeting with editors and reporters of The Washington Post. "I think the United States would be a good place for it."

Ortega said his Marxist Sandinista goverment would announce "concrete proposals and conditions" for a cease-fire today. But he said he could not be more specific because discussions were still going on with Wright about "refining various points" and more talks also were required with Obando, who was flying to Washington last night from Managua. However, sources familiar with the situation said that Ortega was trying to arrange a meeting today between himself, Wright and Obando that would result in the speaker putting his political authority and prestige behind Obando taking on the go-between's role.

The sources said that Ortega also is hopeful that the speaker will possibly assign an aide to act as his unofficial observer in the talks and, if a cease-fire is achieved, send a congressional delegation to Nicaragua to verify that the Sandinistas are complying.

In turning to Wright, Ortega appeared to be attempting a flanking move to force the Reagan administration into bilateral talks that Managua has been seeking without success. Reagan said Monday that if the Sandinistas begin serious indirect talks with the contras on a cease-fire, he would agree to resume discussions with Nicaragua. But, he said, the talks would be only in a regional context that must include the other four countries in the Central America peace agreement signed in Guatemala last Aug. 7.

In a speech Wednesday to the Organization of American States, Ortega charged that Reagan's conditions broke a promise for bilateral talks in the bipartisan Central America peace initiative put forward by Reagan and Wright last August.

An early draft of the Wright-Reagan initiative did speak of "bilateral negotiations." But in the official version released by the White House Aug. 5, the word "bilateral" was dropped. And the text, while saying that the United States would negotiate with all five countries on security issues after a cease-fire had been achieved, did not specify a bilateral or multilateral context.

White House spokesman Marlin Fitzwater said yesterday that he could not deny there had been informal discussion of bilateral talks while the Wright-Reagan initiative was in the planning stage. However, he added that all subsequent discussions had centered on dealing with the Sandinistas "in a multilateral context and a regional context, and I'm not willing to go back and discuss anything that would indicate otherwise."

Wright, a strong supporter of the Guatemala accord, twice has refused Sandinista requests that he be the intermediary in cease-fire talks. However, since Ortega's arrival here Tuesday, Wright has met twice with the Nicaraguan president and has conferred with contra political leaders.

He also met yesterday with Secretary of State George P. Shultz, but State Department spokesman Charles E. Redman said last night that the meeting had been scheduled for several days and that Wright did not inform the secretary that there was a possibility of his meeting today with Ortega and Obando. Shultz learned of it later, Redman said.

Redman reiterated administration statements that Ortega's offer to talk to the contras through Obando, the Roman Catholic primate of Nicaragua, was "a positive development." But, in a clear distancing of the administration from Wright's activities, Redman added, "We don't think it is desirable for the United States to inject itself directly into these talks."

The sources said that Wright, in his discussions of a possible role, was seeking to avoid the impression that he is encroaching on Reagan's foreign policy authority. The sources said he also reportedly has insisted that the conditions Ortega will propose for a cease-fire be acceptable to the contras and Obando as a basis for discussions.

Before leaving Managua yesterday, Obando said he was coming here "to see if it is possible for the parties in conflict to achieve a cease-fire." He did not elaborate except to say, "I will try to talk to any person who I think can contribute to peace in Nicaragua."

Bosco Matamoros, a spokesman for the contras, said last night that resistance leaders believe the talks should be in Nicaragua because "it is our homeland and the center of our conflict." He added that the contras hope "Mr. Ortega will be reasonable on this point." But he also said that if the Sandinistas insist on negotiations in this country, "we will make the extra effort for peace and consider very carefully the Sandinista proposals."

According to the sources, Ortega's proposal will be limited to cease-fire issues, as called for by the Guatemala agreement, and will avoid discussion of a future political role in Nicaragua for the contras.