Manila — The nationwide rallies that marked the second anniversary of the assassination of opposition leader Benigno Aquino Jr. last week showed more divisiveness than unity among the Philippine opposition. Although both moderates and leftists demanded justice for Mr. Aquino's assassination and called for the resignation of President Ferdinand E. Marcos, they demonstrated separately -- which only highlighted the problems that currently beset the political opposition. At the same time, Filipinos' interest in the ``parliament of the streets'' appears to be waning: they are more interested in the possibility of formal political power for the opposition, which could come about if the groups achieve a measure o f unity.
Aquino's widow, Corazon (Cory), led the moderate opposition groups in the rally, while the leftist contingent was led by Lorenzo Taada, head of Bayan -- the new nationalist alliance of leftist organizations.
Ideological lines have been markedly drawn between leftists and moderates since last May, when they failed to forge what was intended to be a ``united front'' against President Marcos. The moderates, who are in the minority, claimed that the well-organized left was running roughshod over them. And the leftists claimed for themselves a larger representation in the united front's highest decision-making body because of their larger numbers.
But some here see the possibility that the political parties and other moderate opposition forces will yet get together for local elections scheduled for 1986.
The left would reportedly form a temporary alliance made up of the underground communist National Democratic Front and the left-leaning Bayan. The two said they will field or support candidates on a ``selective basis'' for that election.
The left has not yet made public, however, whether or not it would participate in the early presidential election Mr. Marcos is expected to call this year -- two years ahead of schedule -- in response to the opposition's attempt to impeach him earlier this month. Such participation would be a prime opportunity for leftist groups and moderates to work together, many observers here believe.
For their part, the moderate opposition groups, which constitute the legal opposition, are preparing to field a common presidential candidate in case of snap elections. Their candidate choices have been narrowed down to two, former senators Salvador Laurel and Jovito Salonga.
Mr. Laurel already proclaimed his bid for the presidency in June. Mr. Salonga has not yet openly declared his intention to run. But many oppositionists say he will not turn his back on an offer to be their standard-bearer.
Should deadlock occur over who should be the opposition's common choice, many believe a campaign to draft Corazon Aquino would snowball quickly. Aquilino Pimentel, chairman of the Pilipino Democratic Party, said Mrs. Aquino is a unifying factor for the opposition.
Some here believe that Laurel, who is insistent about running for the presidency, might give up his ambition if Mrs. Aquino runs.
Mrs. Aquino has always been unequivocal about her lack of interest in the presidency. But lately she has indicated willingness to reconsider her position.
``I'll wait for the opportune moment,'' she said in answer a question on her presidential intentions. ``I'll postpone my answer. Can we wait for the groundswell? For the people to tell me. . . ?''
People were telling her something in the moderates' rally Wednesday: The crowd of 30,000 chanted ``Cory, Cory'' and waved ``Cory for President'' banners as she prepared to speak.
As things stand, the rift between leftists and moderates has remained unhealed. But Agapito Aquino, brother of the slain senator and a moderate, said the moderates are keeping communication lines open to the left.
``We can work with them on a case-by-case basis,'' he said.
The left maintains the same stance. J. Virgilio Bautista, a Bayan official, said dissension in the opposition is only a phenomenon in Manila -- provincial opposition groups have come together well.
That the streets are no longer teeming with as many demonstrators as a year ago (an estimated 60,000-100,000 rallied nationwide this year, as opposed to 500,000 in 1984) is not seen as an entirely negative development by opposition observers here. Many believe that the previous strong emotions have crystallized into a desire to tackle broad, long-term issues.
Now the oppositionists are calling for the dismantling of the Marcos ``dictatorship'' more than for the ``continuation of the struggle of Ninoy [Aquino].''
Opposition groups that sprouted after Aquino's assassination are also said to be busy organizing -- rather than marching in the streets.
But the main cause of this year's trimmed-down rallying was last year's National Assembly elections. The opposition's surprising gains in parliament (it had had only a toehold since martial law was imposed in 1972) have given rise to expectations that reforms can be achieved through the legislative process.