Manila — The underground Communist Party of the Philippines feels that it has everything to gain from the new political situation here, provided it can survive the turmoil it sees coming in the next few months.
The assassination last month of opposition figure Benigno Aquino keeps the political center leaderless. More important, the Communists believe, the murder - still widely assumed to be the work of senior government officials - has dealt a near fatal blow to the government's credibility.
Equally important, the Communist Party of the Philippines (CPP) hopes, the murder has convinced most members of the liberal opposition of the perils of determined opposition - even legal and nonviolent - to the government.
Like many other Filipinos, a CPP cadre interviewed shortly after the assassination saw the killing as the product of a power struggle at the top of the Philippine government.
''The killing was just a prelude,'' said the cadre. ''Our analysis is that Marcos will be dead within three months. Then we anticipate a massive military crackdown that will be much worse than in 1972 (the year martial law was declared).''
The crackdown will, the CPP believes, be launched by the two people most likely to succeed Marcos, Gen. Fabian Ver, armed forces chief of staff, and Mrs. Imelda Marcos, the President's wife.
''Ver and Mrs. Marcos don't have the respect that Marcos could command in 1972,'' said the cadre. ''They will hit out at any group that seems to pose a threat to them.''
While official statements distributed by the underground place the blame for the Aquino assassination firmly on President Marcos, Mrs. Marcos, and General Ver, the cadre ruled out direct complicity by President Marcos in the killing.
''Marcos had nothing to gain by the murder,'' said the cadre. ''Ver and Imelda were the ones really threatened by Aquino's return. They would never have been endorsed (as Mr. Marcos's successors) if Aquino was back in the country.''
The cadre also excluded the CPP's archenemy, the United States, from any involvement in the killing.
''The US was grooming Ninoy (Aquino's nickname) as an alternative to Marcos, '' said the party official. The Aquino family would probably disagree: Mr. Aquino's widow, Corazon, says that the Reagan government basically ignored him.
''Ninoy could be relied on to some degree to protect their interests. It would not have been possible for the US to consider killing him.''
The cadre also denied any CPP involvement in the murder.
Leaving aside ''technical problems, such as infiltrating the Aviation Security Command from top to bottom,'' the cadre said, the assassination of opposition leaders ''just isn't our style. We are trying to establish alliances with them, and are doing quite well.
''We did not regard Ninoy as an enemy. Though we failed to convince him of the US role here, he made a great contribution to exposing the true nature of the Marcos regime,'' the cadre said.
The cadre repeated the underground's claim that they had offered Aquino sanctuary in zones controlled by the CPP's armed wing, the New People's Army (NPA).
''About two months before Aquino returned, our sympathizers in the United States gave him a formal standing offer to go to liberated zones in either Luzon or Samar,'' the cadre said.
Aquino never replied, however, and this was interpreted by the Communist Party as an ''implicit refusal,'' the cadre said. CPP contacts with Aquino while he had been in the US had been limited, the cadre said.
Aquino was, however, an ''extremely effective politician,'' the cadre added. Though he was trying to reach an agreement with President Marcos, the CPP was optimistic that, once he had seen what was happening in the country, he would have been open to cooperation with the underground.
The CPP is thought to have established a good working relationship with one of the top opposition leaders, former senator Gerardo Roxas, who died in 1982. They may have been hoping to do the same thing eventually with Aquino.
The assassination of Aquino, however, should help the party in its efforts to establish what it calls a broad alliance with the liberal opposition.
''The liberals have their backs to the wall,'' said the cadre. ''They are finally beginning to realize how ruthless'' Philippine politics has become. The cadre claimed that, to various degrees and for varying reasons, most opposition politicians were prepared to cooperate with the CPP. ''But as usual (former Sen. Salvador) Laurel and (former Sen. Eva) Kalaw haven't made up their minds yet. But of course they have links with the (presidential) palace.''
The cadre admitted surprise at the large size of the popular response to the Aquino murder. ''We now have to transform the popular anger into organized anti-regime activities,'' said the cadre. The party was trying to put the killing into a broader, radical, political framework - ''relating Aquino's murder to the killing of other activists struggling for national democracy.''
The party obviously views these activities as vital not just for longterm. It will at best be an uncomfortable spectator in any power struggle that follows President Marcos. More probably it will be one of the main targets of any crackdown that follows Mr. Marcos.
Its armed wing, the NPA, with an estimated 7,000 guerrillas is as yet no match for the government forces in a confrontation. It has contingency plans to pull more of its political structure totally underground should the need arise, the cadre said, ''but basically our survival will depend on how well we organize the people in the months to come.''