Nicaraguan President Daniel Ortega yesterday called for a month-long cease-fire in his country's civil war to begin Dec. 5. With an assist from House Speaker Jim Wright (D-Tex.), Ortega proposed that his plan be the basis for indirect negotiations through Nicaraguan Cardinal Miguel Obando y Bravo with U.S.-backed contra rebels.

White House and State Department officials angrily criticized Wright's involvement with Ortega, complaining that he may be undercutting U.S. policy in Central America.

Wright insisted to reporters that he was responding to requests to help the Central American peace process and not interfering "where I'm not invited and not welcome."

But White House spokesman Marlin Fitzwater said, "We don't believe it's in the best interests of peace to have the U.S. negotiating with the Sandinistas."

State Department spokesman Charles E. Redman, asserting that Secretary of State George P. Shultz has only the sketchiest information about Wright's activities, implied that the speaker's efforts might weaken the administration's strategy of putting pressure on the Sandinistas through continued support for the contras.

The dispute was a manifestation of the tensions produced by weeks of political maneuvering since Wright first entered Central American diplomacy by proposing a peace plan jointly with President Reagan. Their alliance lasted only a few days, and since it broke down the speaker has been pressing the administration to do more to encourage the peace process initiated by Nicaragua's neighbors in Central America.

While Wright and administration officials were sparring yesterday, Obando said he still has not decided whether to accept the intermediary's role, leaving it unclear whether negotiations for a Nicaraguan cease-fire might finally begin.

Obando, Ortega and Wright met early yesterday in the residence of the papal representative in Washington, Pio Laghi. Ortega gave Obando an 11-point proposal from his Marxist Sandinista government calling for a cease-fire from Dec. 5 to Jan. 5 and offering amnesty to any contras who lay down their arms during that time.

Those who accept the amnesty "then may join in the political life of the nation with full enjoyment of their rights" including participation in the national reconciliation dialogue launched by the Sandinistas Oct. 5, the plan added. But it also stated that during the period of the cease-fire, the contras in the field could not receive any military supplies -- a condition that would cut off deliveries of U.S. arms and equipment.

Several hours after receiving the Sandinista plan, Obando met separately with Ernesto Palazio, the Washington representative of the contra movement's six-member political directorate. Palazio said later that Obando did not relay to him Ortega's proposals. Instead, according to Palazio, the cardinal accepted a communication from the contra directorate and said that he would use the positions outlined by the two sides in deciding whether to become the mediator.

Palazio said Obando indicated to him that he first wanted to consult the Nicaraguan bishops' conference. Palazio also indicated that the cardinal was troubled by continuing disputes over a site for the talks. Ortega has rejected the idea of negotiations in Managua or elsewhere in Central America, but Palazio said the cardinal appeared yesterday to agree with the contras' argument that Managua is the logical site.

In addition, Wright, discussing with reporters the meeting at the nuncio's residence, said that Obando has some unresolved concerns about how much authority and flexibility the two sides will allow him if he becomes the intermediary. "I see some rough areas that are going to need to be smoothed out," Wright said.

However, Wright also said: "I am very happy that at least one more step seems to be moving in this progression toward peace. It is not yet at hand, but movement continues in that direction, for which I am grateful."

Despite Wright's attempts to play down the importance of his efforts, it was clear that he had exerted considerable influence on the events of the past week. Among those at the meeting at the nuncio's residence was Paul Warnke, who was director of the Arms Control and Disarmament Agency in the Carter administration.

When reporters asked why Warnke was there, Wright said it was at the nuncio's invitation. But later he acknowledged that the invitation came about because Wright had been asked for the names of some experienced negotiators with whom the cardinal could consult. He said that he had suggested Warnke and Philip C. Habib, Reagan's former special envoy for Central America who resigned last summer because of the administration's reluctance to take an active negotiating role in the Central American peace talks.

Wright said that if indirect talks between the contras and Sandinistas begin, he would be willing to designate members of Congress to act as occasional observers of the process and, if a cease-fire results, to send congressional staffers with experience in military matters to monitor its effectiveness.

Wright's efforts to promote indirect talks is the latest of several attempts to promote the peace process in Central America. This sequence began Aug. 5 when Wright and Reagan issued a bipartisan Central America peace initiative, which encouraged the presidents of Nicaragua, Costa Rica, El Salvador, Honduras and Guatemala to meet in Guatemala and sign a peace agreement two days later.

When the Central American leaders adopted a somewhat different plan that the administration considered imperfect, Wright promoted their proposal by inviting its principal author, Costa Rican President Oscar Arias, to appear before Congress with a plea to "give peace a chance." Wright also has used his influence on Capitol Hill to force the administration to postpone until after the new year its request for $270 million in new military aid for the contras.

Asked yesterday about administration criticism of his latest moves, Wright replied that it was the White House that originally invited him into the process last summer. He said he had heard no complaints from Reagan or Shultz and added that when he told the secretary about the meetings with Ortega, Shultz had replied, "Fine, good. I hope it works."

Ortega's proposals specify that during the month-long cease-fire, contra forces must go to one of three zones with a total area of 10,000 square kilometers. Fifteen days before the start of the cease-fire, Sandinista troops would halt offensive operations to permit the rebels to move to these zones.

While the rebels could not receive outside military, financial or public relations support, they would be given clothing, food and medical care by a mutually agreed-to neutral agency.