Undated (AP) _ By DAVID BRISCOE Associated Press Writer

MANILA, Philippines (AP) - Corazon Aquino, who was made both a widow and presidential candidate by an assassin's bullet, says she would try to solve the growing communist insurgency by negotiation and eventually wants to remove U.S. bases from the Philippines.

In a 90-minute interview Wednesday, the day after she declared her candidacy, Mrs. Aquino said Ferdinand E. Marcos has built the best political organization in Philippine history during his 20 years as president, but she hopes to raise millions of dollars and get quiet support from the Roman Catholic Church.

She expressed a ''fatalistic'' attitude toward of the possibility that she, too, may be killed but said she had agreed to have four bodyguards.

Mrs. Aquino, 52, accuses Marcos of masterminding the killing of her husband, opposition leader Benigno Aquino, who was shot in the head as he stepped from a commercial airliner that brought him home from self-exile in the United States in August 1983.

On Monday, 25 military men and a civilian were found innocent of charges that they conspired to kill the former senator, who was Marcos' leading political foe. Most prominent among the defendants was Gen. Fabian C. Ver, the armed forces commander, an old friend and confidant of the president.

Marcos has said the major issue facing the Philippines is a communist insurgency, in which the government says an average of 10 people are killed every day. The president says only he can quell the rebellion.

Speaking at dinner in the family's one-story home in a Manila suburb, Mrs. Aquino said of the guerrillas: ''I will ask for a dialogue with them, maybe not me personally but someone representing me, so that all of this fighting and killing will stop.''

She said she did not think communism would work in the Philippines because Roman Catholicism is so deeply rooted, but she added: ''If we moderates lose in the coming election, maybe some people would say, 'The whole thing is hopeless, let's just switch over to the communists.'''

About U.S. military facilities here, Mrs. Aquino said, ''I am for the removal of the bases, although I am not for the immediate removal of the bases.''

The current agreement on bases, which include Clark Air Force Base and the Navy base at Subic Bay, runs until 1991. Mrs. Aquino said at her first news conference as a candidate that she would honor it.

She said in the interview, without elaborating, that steps should be taken to make sure no other foreign power is granted bases in the Philippines before the U.S. installations are removed and that the matter should be discussed with other Asian nations.

Her decision to run for president came after she talked with a priest who told her Filipinos do not want Marcos any longer but had not supported the opposition because no one personified its calls for truth, justice and freedom, Mrs. Aquino said.

Does she expect support from the Catholic church, to which 85 percent of the islands' 53 million inhabitants belong? ''I should certainly hope so but, of course, they can't do it publicly,'' she said.

Some priests and nuns have supported the opposition openly, and top church leaders have criticized Marcos' rule, which included eight years of martial law beginning in 1972. The church is considered a potentially strong political force, but its leaders say it does not back candidates.

''Marcos has definitely the best organization ever,'' Mrs. Aquino said. ''Certainly it has been well-oiled the past 20 years. He has certainly all the funds necessary and more than that.''

Mrs. Aquino said she does not expect an easy time against the president. ''I think Marcos won't allow anyone to succeed him,'' she said. ''I'm not naive enough to think that he'll make it easy for anybody.''

She would not say whether she had agreements on financial support before she made her candidacy public Tuesday, hours after Marcos signed the law setting the special presidential election for Feb. 7.

Advisers think she will need $14 million to $28 million to run a national campaign, Mrs. Aquino said, and she feels she can raise the lesser amount from businessmen and other supporters.

Marcos has not said how much he plans to spend, but Mrs. Aquino's brother- in-law, Agapito Aquino, estimates it will be at least 10 times the opposition's budget.

Mrs. Aquino said her only qualification for candidacy was the 28 years she spent with her husband while he served as a mayor, provincial governor and senator.

She comes from a prominent family, the Cojuangcos of central Luzon. Her father and a brother were congressmen and her maternal grandfather was a senator. The family owns a sugar plantation, sugar mill and distillery.