After shocks of disagreement and indecision, the [WORD ILLEGIBLE] accused of Nicaragua's political opposition, including spokesmen for guerrilla leaders, announced yesterday that they have consolidated and cleared the way for a democratic provisional government to replace President Anastasio Somoza.

While it is still [WORD ILLEGIBLE] and when Somoza will give in to its demands for his resignation, the opposition took the long-argued and delayed step of appointed a three-man commission with authority to speak for all its factions.

These range from traditionally conservative politicians and millionaire industrialists to the guerrilla Sandinista Liberation Front.

Somoza has derided their disparity, saying he could not negotiate with his opponents because he did not know who they were. At the same time, other governments that have privately and publicly supported the call for Somoza's departure had begun to despair of any cohesive democratic leadership to take his place.

The new commission is empowered to negotiate a cease-fire in the bloody nationwide fighting and to link the opposition to a mediation effort by an outside government.

Governments envisaged for such an effort, according to Sergio Ramirez, a 36-year-old attorney and author who is one of the three, include Venezuela, Costa Rica, Panama, Mexico, Colombia or the Dominican Republican. Some of those governments already have offered to mediate. Ramirez said and cables are being sent to the others.

The United States will not be asked, Ramirez said, because "we prefer Latin American countries." The Somoza government has not responded to outside calls for mediation thus far.

Other members of the three-man group are opposition leaders Rafael Cordova Rivas, 54, and Alfonso Robelo, a 38-year-old industralist.

A cease-fire, Ramirez said, is the commission's most immediate task.

"Hundreds of people are being killed," he said, and "entire cities are being wiped off the map."

Some opposition leaders also see the three as probable members of a future provisional government.

While Ramirez said the opposition coalition is willing to negotiate a cease-fire with government representatives, it will not deal directly with Somoza and any acceptable solution to the crisis must include his resignation.

The consolidation announcement came as fighting between civilian rebels and guerrillas and Somoza's National Guard escalated in cities throughout the country and the opposition's political leadership began to appear less and less in control of the situation.

While 15 leading civic and political opposition groups several months ago organized under the umbrella Broad Opposition Front, the front itself has had no clear leaders and has seemed primarily a forum for disagreement and indecision.

Among its membership are three factions of the traditional opposition Conservative Party; a recently formed liberal businessmen's party called the Nacaraguan Democratic Movement (MDN); a liberal splinter from the Conservative Party called UDEL; and a dozen more civic, political and business groups.

The Broad Opposition Front also includes the Group of 12, a collection of priests, prominent professionals and industrialists who joined last year to oppose Somoza and call for support for the guerrillas.

Each group has had its own plan for a post-Somoza government and its own idea of who the leaders of such a government should be.

Several weeks ago, the long-bickering Conservative Party factions reached an accord for unity. Their plan for a new government calls for the election of a new president from party members within the 100-member Congress, in which they - as the only legal opposition party - are in the minority to Somoza's Liberal Party.

That president would serve until scheduled elections in 1980.

The Conservative Party has insisted that its plan falls within the provisions of the Nicaraugan constitution for replacement of the president, and would thus preserve the country's legal infrastructure. But other groups in the Broad Opposition Front have opposed the replacement provisions.

The others, including the Nicaraguan Democratic Movement and UDEL, have argued that neither the people nor the Sandinistas will accept a new government drawn from the ranks of the old parties, even from members of the legal opposition.

"Our optimum solution," said one front member, "is the appointment of a provisional civilian council," ideally a combination of leaders from various front groups, "that would rewrite the constitution and hold elections within three years."

The provisional government council now seems the most viable option for a new government, with the three newly appointed commission members the most likely candidates.

Cordova Rivas is an attorney who heads UDEL. While some of the younger opposition leaders feels he lacks polish, he is an expansive populist who is well known and respected in the countryside.

Robelo, an engineer and vegetable oil producer who began the Nicaraguan Democratic Movement last summer, is little known outside Managua business and political circles. But he is a likable and shrewd strategist who is highly thought of by the U.S. Embassy here and the State Department.

Ramirez is a member of the Group of 12. Of the potential future leaders, he is considered closest to the Sandinistas.

Other possibilities within the Conservative party include Eduardo Chamorro Coronel and Rene Sandino Arguell, both anti-Somoza conservatives, and Julio Molina, a Congressman who is a reformist renegade within the party.

Important disagreements still exist between the Conservatives and other front groups. Both sides feel that a decision cannot be made on the form of a new government until the departure of the old is assured. But with the appointment of the new commission, both sides say they have signaled their consolidation into a common force and their joint intentions to abide by whatever eventual decision is made by the majority of their members.

"There is now a consensus between the FAO and the Conservatives," a Conservative congressman said, "to present a common front before the United Nations and the Organization of American States. We want to send a delegation to Washington and to New York, to show them we are all united."

Key to the popular acceptance of any new government is the support and participation of the Sadinista guerrillas.

"We can't deny that the sympathy of the people is now with the Sandinistas," said the congressman. "Not necessarily with a political philosophy, but with them as defenders of national sovereignty."

A flood of Sandinista communiques over the past week apparently has been intended to demonstrate the degree of unity within the guerrillas' own previously faction-ridden ranks and to calm fears that they plan a marxist takeover.

Over the weekend, the guerrillas called on their supporters to organize in support of a provisional government and named the Group of 12 as their delegate in discussions with other opposition groups. Their two fundamental demands for such a government, they said, are expropriation of all Somoza's property and formation of a new army to replace the national guard.