Aqui Macombo, he radioed off into the night. "Macombo here."

With the aid of bifocals to shift frequencies in the dark, the gray-bearded commander was making contact with guerrillas he said are scattered in redoubts across 12,000 square miles of southern Nicaragua's swamps and rain forests.

Macombo is the code name now. In another time, another war, it was Commander Zero. But for Eden Pastora, who at 47 has made irregular warfare into a personal mystique, the struggle has never changed, only the enemy and the allies.

"We say no to gringo imperialism, but also to Russian imperialism," he fumed, standing legs apart and chest thrust forward. "Now that we are struggling against another dictatorship -- the same ones who struggled against the first one -- the left and the right again agree to call us erratic, mercurial, incoherent and picturesque."

Because of decisions in Washington, this is a difficult moment in Pastora's lonely fight. The CIA indirectly funneled between $300,000 and $400,000 a month to his forces from October 1983 to February 1984, he said, but since then has cut off the funding and gone out of its way to hinder his actions.

With the CIA money and $600,000 he said he received when Francisco Fiallos defected as Nicaragua's ambassador to Washington in January 1983 with the embassy bank account, Pastora claimed to have built a guerrilla force of 7,000 men who ambushed the Popular Sandinista Army from the Costa Rican border as far north as the Escondido River and the strategic Rama Road leading to Bluefields on the Atlantic Coast.

But that was last year. This year, Pastora acknowledged after some prodding, only 2,000 men are involved in the war, and each of these has only a handful of ammunition. In the crackling radio conversations he had with his followers, Pastora advised them to do political work among the peasants if they could not fight.

Pastora, who has more than 20 years' practice in the back rooms of revolution, said he knew a place in Panama where he could get 3 million rounds of ammunition for $500,000. But according to a recent conversation with his accountants back in San Jose, Costa Rica, he admitted, the ragged army that would bring democracy to Nicaragua had the equivalent of $63 in its war chest.

Costa Rican authorities have cut off the telephones at his rear headquarters in San Jose because his political allies could no longer pay the bills. The Clinica Biblica, a San Jose hospital where he was initially treated for burns when a bomb exploded at his feet in an assassination attempt last May, is still dunning him for monthly payments on that bill.

A clinic in Caracas, Venezuela, where he convalesced for weeks afterward, has not been paid either, he said, even though his followers have sold trucks, airplanes and their wives' jewelry, and even though Pastora hocked a prized gold Rolex watch presented to him by the Sandinista National Directorate back in the glory days after they overthrew Anastasio Somoza in 1979.

"The CIA is a son of a bitch," Pastora declared.

As Pastora described it, the CIA confiscated his one operational helicopter, a Hughes 500 that he used to ferry wounded combatants from inside Nicaragua to Costa Rican hospitals. In his view, the CIA also was behind the brief detention of his lone Beechcraft light airplane last week in Tegucigalpa, Honduras, where it had flown to pick up supplies donated by Cuban emigrants in Miami.

Alfonso Robelo, who was allied with Pastora in the Revolutionary Democratic Alliance, said the helicopter and some disputed light airplanes came under his control because their pilots deserted Pastora when the two leaders fell out last summer. The alliance, called ARDE by its Spanish initials, split when Robelo made an alliance with the main Nicaraguan rebel group, the Nicaraguan Democratic Force based in Honduras, and Pastora refused to go along on the ground that the northern guerrillas include former enemies from Somoza's National Guard.

But for Pastora, the loss of aircraft reflects a decision in Washington to reach a negotiated accord with the Sandinista government in Managua. And since he will not accept the new direction, Pastora said, the Reagan administration has put obstacles in his way through "the CIA, with its black hands that, if you touch them, you end up with manure."

On the muddy banks of the San Juan River, where Pastora makes his operational headquarters in a shack on stilts, the shifting politics of Washington appear flaccid and often treacherous to a perennial warrior who proclaims his goal simply is to bring justice and freedom to his people.

"In these 25 years [of guerrilla warfare], I have learned that Washington is a universe that is very difficult to understand," he told some American visitors. "Who's running it? Nobody knows."

So as he strides through the swampy terrain or boats along the network of brown rivers, Pastora seems to have no time for the intricacies of Congress and its relations with President Reagan, or for questions about the wisdom and legality of CIA aid for guerrillas out to overthrow the Managua government.

"The Americans make North American politics out of Nicaraguan politics," he snorted.

For Pastora, the problem is clear, painfully clear, as it has been since he was 7 years old and an officer in Somoza's National Guard killed his father. The memory of that moment -- and his mother's cries when news reached the family as they sat down to dinner -- helped steer him toward the Sandinista National Liberation Front and its revolution against the U.S.-backed dictator.

After leading the takeover of the National Palace in Managua in 1978 and capturing the imagination of his countrymen as Commander Zero, Pastora went on to lead the southern front during the Sandinistas' final offensive in June and July the following year.

He served as deputy interior minister and deputy defense minister after the Sandinista takeover. In fact, he recalled with a smile, he led the first Sandinista Army battalion into northern Nicaragua to hunt National Guard remnants who already in 1980 had begun sabotage raids from Honduras.

"And I was, and I continue to be, the most loved commander in Nicaragua," he declared.

For this reason, he said, the CIA last year tried to entice him to join Robelo in associating with the Nicaraguan Democratic Force. He refused, he explained, because he would not lend his "legitimacy" to a movement that, in his view, will never command the loyalty of the Nicaraguan people as long as its leadership includes former National Guard officers.

It was similar rigidity that led Pastora to leave Nicaragua in July 1981 -- two years after the Sandinista victory he had fought for -- and to denounce the Sandinista government in April 1982 for what he described as repressive tactics and a sellout to Cuban and Soviet influence.

The Sandinistas in Managua call him "the traitor" for his switch. But Pastora insisted that it is the government that has betrayed the principles of Sandinismo.

"Sandinismo, in its essence, is the defense of national sovereignty," he lectured on the heritage of Gen. Augusto Sandino, the 1920s rebel who gave the movement its name. "Sandinismo is nationalism. And the Sandinista government in Managua is not nationalist, it is internationalist. That is one of the principles of Marxism, this internationalism."

That is why his guerrillas are the true soldiers of Sandinismo, Pastora proclaimed.

"I criticize the U.S. threats against Nicaragua," he said. "But I am also combating the Cuban invasion of Nicaragua. You have to have [courage] to do that."

As he told it, Pastora's fate was drawn when the Sandinista leadership decided one month after its 1979 victory to support the Salvadoran guerrilla movement. For Pastora, this was fraternal aid to a fellow revolutionary movement. But to Tomas Borge, the Nicaraguan interior minister and ideological patriarch, it was rather "the negotiations element," Pastora recalled.

Now, viewed from the banks of the San Juan River, at least, Borge's strategy is bearing fruit. Pastora said the U.S.-Nicaraguan talks in Manzanillo, Mexico, are heading toward agreement under which the United States would end pressure on the Sandinista government and Nicaragua would halt support of the Salvadoran guerrillas.

That would leave his people under the rule of "tropicalized Stalinists" bent on imitating Cuban communism for Nicaragua, Pastora said. This he will not tolerate, even if the United States makes a permanent fund cutoff to the rebels part of the deal.

"They can shut down the north, but they cannot shut down the south," he vowed. "No, no. I will go on with my little war here."