Washington — Despite coming elections in both El Salvador and Nicaragua, the prospects for Central America in 1984 may be for intensified warfare. In fact, some members of the United States Congress are convinced that the elections in both nations may end up legitimizing political leaders who are opposed to negotiated resolutions of the fighting.
This is why a ''third option'' between what are perceived to be extremes of left and right, which is being proposed by Costa Rica-based rebels fighting the Sandinista-led Nicaraguan government, is gaining support in Congress, particularly among Democrats.
Although the loudest debate in the Congress has focused on administration requests for military aid to El Salvador and for the CIA-supported, Honduras-based rebels fighting the Sandinistas, quiet moves are under way to respond to the group of third-option advocates. These are members of the Democratic Revolutionary Alliance (ARDE) based in Costa Rica.
An ARDE leader, Alfonso Robelo Callejas, is in Washington talking with members of Congress. Mr. Robelo is allied with Eden Pastora Gomez, better known by the guerrilla name of Commander Zero. Mr. Pastora was a hero of the Nicaraguan revolution who gained worldwide publicity when he and his men captured the National Palace in Managua in 1978.
ARDE argues that an opportunity exists for the planned November elections in Nicaragua to lead to an end to the fighting there and to a reconciliation among the Nicaraguans who are now at odds with each other. But for this to happen, ARDE leaders say, foreign nations, including the United States, should encourage an election in Nicaragua that permits, first of all, the participation of all representative forces in the country.
In an interview here, Robelo said he had not yet been given permission to return to Nicaragua to participate in the Nov. 4 presidential election. He said the Sandinistas had indicated that they would allow the return of former junta member Arturo Cruz Porrasto to contest the election. But he added that the Sandinistas recently organized a group of demonstrators who called for Mr. Cruz to be taken to the firing squad.
Robelo says Cruz is the candidate who could best unite the opposition forces in Nicaragua. A former Nicaraguan ambassador to the United States, Cruz works at the Inter-American Development Bank in Washington. In an interview last month, Cruz said that what the Sandinistas had offered so far in the way of conditions for the November election was not enough to ensure that the election would be free. At the same time, he said, pressures could lead the Sandinistas to ''cut a political deal.''
With this possibility in mind, Massachusetts Democrat Edward M. Kennedy is leading a move in the US Senate to get senators to sign a letter calling on the Sandinistas to hold free and fair elections. The Senate Democratic Policy Committee is also considering such a move.
''We're basically responding to ARDE,'' one key Senate aide says. ''I think we'll get a significant number of signatures on this.''
Robelo argues that congressional Democrats - and some liberal Republicans - have an obligation to call for an opening up of electoral conditions, because it was with Congress's encouragement that the Somoza dynasty was overthrown in Nicaragua and replaced by Sandinista rule.
According to Robelo, one necessary condition for the Nicaraguan election is ''clear signs'' from the Sandinistas that they are willing to start separating the Army's functions from those of the ruling Sandinista party. ARDE is also calling for a restoration of all public liberties; clear guidelines permitting political party participation; and Latin American supervision of the election, linked with a permanent mission in Nicaragua from the Inter-American Commission on Human Rights.
''If we don't get help on this from the Congress, the Socialist International , and Democrats in Latin America, the extremists from both right and left will be in charge,'' he adds. ''You may end up with a regional war in Central America , and that could mean that American troops would be involved.''
Robelo said that ARDE was currently receiving aid from Venezuelans, Germans, Spaniards, Mexicans, Nicaraguans in California, and ''some Jewish communities'' in the US. He said he knew of no aid received from the US Central Intelligence Agency.
''We have been receiving aid from different sources,'' said the bearded Robelo. ''If these sources are receiving their money from the CIA, and it's going through them, honestly it is not our business. . . . Aside from that, if the CIA gives us money we will take it. But we will not take orders from the CIA.''