Pieces are falling together that could lead to the first negotiations aimed at ending the war in El Salvador. It would be too much at this point to say that administration officials are optimistic. Statements from all parties to the conflict seem to contain a strong element of posturing.
But officials say that Richard Stone, President Reagan's special envoy to Central America, is leaning in favor of a meeting with the Salvadorean guerrillas.
Ruben Zamora, a spokesman for the guerrillas, was to arrive here June 15, ostensibly for routine meetings with congressmen, their aides, and others interested in El Salvador. Mr. Zamora had said earlier that the Revolutionary Democratic Front (FDR), the guerrillas' political front, was prepared to talk with Mr. Stone, a conservative Democrat and former senator from Florida.
El Salvador's president, Alvaro Magana, is also coming to Washington. He will meet with President Reagan on June 17. Mr. Magana will be accompanied by a delegation of high-level Salvadorean officials, including the defense and foreign ministers.
Thus within a matter of a few days, key players, as they are called in Washington, will be in place to pursue peace, if they have the will to do so. The danger is that a highly publicized meeting could turn into a propaganda competition for all concerned, and thereby even set back the chances for peace.
A meeting with guerrilla representatives would, of course, require President Reagan's approval and the acquiescence, if not the approval, of the Salvadorean government. But State Department officials say that Stone's only real problem at this stage is likely to be with conservative ''ideologues'' in the administration who apparently fear serious negotiations and do not want to confer any legitimacy on the guerrillas.
A meeting with the guerrillas might, on the other hand, have the advantage for the administration of securing some congressional votes. A key House subcommittee, headed by Democrat Clarence D. Long of Maryland, is soon supposed to consider the administration's proposed 1984 aid bill, including $85 million in military aid for El Salvador. Mr. Long has said that he may tie future aid to El Salvador to negotiations. He has accused the administration of seeking a military solution.
The alliance of leftist-led forces in El Salvador recently sent a letter to Stone suggesting that a meeting be held ''in the presence of witnesses from the US Congress.'' Publicity given to the letter, as well as the proposal for witnesses, suggested to some US officials that the guerrillas were more interested in scoring propaganda points than in negotiating. But a spokesman for the FDR later said that while the guerrilla representatives desired the presence of congressmen, it was not a precondition.
The Salvadorean government has proposed talks with the guerrillas concerning conditions for elections, at which other subjects can be raised.
Despite his hard-line reputation, Stone has impressed some observers as a man who is sincerely probing possibilities for a negotiation. A State Department official said that because Stone's right flank is protected by his reputation, he may be able to probe more actively than would a liberal in the same position.
''It may be like Nixon making the opening to China,'' the official said.
''Stone is more thoughtful and pragmatic about these matters than some people realize,'' said Robert S. Leiken, a senior fellow and a Latin American specialist at Georgetown University's Center for Strategic and International Studies.
''We met with Stone about a week before his confirmation,'' said an aide to Congressman Long, who made the original proposal that a special envoy be sent to Central America. ''Stone's attitude was very different from what everyone thought. He was very anxious to try to meet with everyone.''