As President Ferdinand Marcos campaigns for reelection to the office he has held for the past 20 years, he assails his opponent with a gamut of accusations: political inexperience, "dalliance" with Communist rebels and advancing the interests of "oligarchs" and American "interventionists." But in a sense, he is running against a dead man.

Increasingly in his campaign appearances, Marcos has been attacking his former political rival, Benigno Aquino Jr., who was assassinated in 1983 and whose widow, Corazon Aquino, is now the contestant in an election set for Feb. 7.

The attacks have opened Marcos up to charges of vilifying the dead or, as one opposition newspaper put it, "ghost-busting, Philippine-style." For the first time, columnist Maximo Soliven wrote, "a dead man has been 'resurrected' from the grave to become a major election issue."

For her part, Corazon Aquino makes no secret of the fact that her positions on various issues are essentially those of her late husband. In her campaign speeches, she has said repeatedly that she seeks justice for the former senator and opposition leader, whose killing she accuses Marcos of having ordered.

At her campaign headquarters in the capital's business district, a visitor might be forgiven for thinking that "Ninoy" Aquino, as he was known, is the opposition's presidential candidate. There are more posters of him and banners bearing his likeness and quotations on the walls than there are of Corazon Aquino.

A reluctant politician who had never before run for elective ofice, Corazon Aquino has said that she reached her decision to oppose Marcos for the presidency after praying for guidance at her late husband's grave. Upon announcing her candidacy on Dec. 3 -- a day after a Marcos-appointed court had acquitted 25 military men and one civilian of Aquino's assassination -- she quoted her husband's words as he began his ill-fated journey home: "I will never be able to forgive myself if I could have done something and I did not do anything."

Marcos has responded by bitterly denouncing the assassinated opposition leader and raising alleged crimes for which he was sentenced to death in 1977 by a military court.

Aquino, the Philippines' youngest governor and youngest senator, was a rapidly rising political star and a leading presidential contender when Marcos declared martial law in September 1972 and called off an election set for the following year.

Aquino was the first opposition leader to be jailed after martial law was proclaimed. He was released in 1980, under pressure from the Carter administration, to undergo heart treatment in the United States. He remained in the United States for three years before returning home in August 1983 in defiance of warnings from the Marcos government. Moments after he was escorted from his plane by military guards at the Manila International Airport, he was fatally shot in the back of the head.

The Marcos government blamed a lone gunman, Rolando Galman, who it said was hired by Communist rebels and who was gunned down on the airport tarmac by security men. An official fact-finding board and several other legal panels found that Aquino was shot by one of his escorts in a military conspiracy, but the government's version eventually was upheld by a special court last month.

The verdict hardly laid the matter to rest. In fact, one opposition newspaper reported, Marcos in recent campaign outings has spent at least a half hour per rally in denouncing his dead opponent, never mentioning his current challenger by name.

"What qualifications does she have except that her husband was killed?" he asked in one appearance. "She always stands up and asks for pity, making believe that there was no reason for her husband's arrest."

In a press conference Friday, Marcos repeated charges that Aquino had participated in establishing the Communist Party of the Philippines nearly 20 years ago, with its original chairman, Jose Maria Sison, at the hacienda Luisita in Tarlac Province, an estate owned by the wealthy Cojuangco family of Corazon Aquino.

In one of the contradictions that have marked his campaign rhetoric, however, the charge is at odds with an account of the Communist Party's history in an official government white paper issued last May.

Entitled "The Communist Insurgency in the Philippines," the white paper, which is distributed with Marcos campaign literature, makes no mention of Aquino as having helped set up the Communist Party. It says the founding took place in December 1968 in a village in the province of Pangasinan.

In addition, Sison, the jailed former party chairman, has denied that Aquino had any role in founding the outlawed party. Marcos "should stop accusing a dead man who cannot defend himself and who was in fact a victim of his regime," Sison said in a statement sent to opposition newspapers from his military prison.

Marcos also has claimed that Aquino financed a raid by Communist rebels on the Philippine Military Academy armory in 1970 and ordered several persons killed during his political ascendancy.

Describing Aquino as "a man who has brought about much suffering in our country," Marcos on Friday rejected any blame for his assassination. "If we had wanted Ninoy Aquino to be disposed of, would it not have been more sensible to just wait for the death verdict to be implemented?" he asked, referring to the sentence handed down under martial law.

In the campaign, Marcos is portraying the alternative to his rule as a bloody slide toward communism. The opposition candidate has termed "preposterous" the charge that she is allied with the Communists, who Marcos has said killed her husband.

In her strongest statement against the Communist rebels waging a guerrilla war in the Philippine countryside, Aquino said last week, "Let it be clear once and for all that I will not hesitate to fight them with every available resource of the republic should they refuse to lay down their arms."

In his news conference Friday, Marcos indicated that he had disregarded advice to avoid making his opponents' slain leader a campaign issue. He said he was obliged to do so because "they made him an issue" and there was now "a need to open up the records of his case, for which he was given the death verdict."

Opposition columnist Soliven wrote, "Mr. Marcos, you cannot fight a dead Ninoy. He has already escaped your clutches, he is beyond pain and libel, and can suffer no more."