When Defense Minister Juan Ponce Enrile ventured in June to the home province of his former mentor, Ferdinand Marcos, amid rumors that he was about to be fired from the government of President Corazon Aquino, he was welcomed with effusive praise.

"You are our new leader, our hero and our father," the mayor of the Ilocos Norte provincial capital of Laoag told him. Another local official addressed him as "Mr. President."

Replied Enrile: "I am not the president yet."

This week, as Aquino begins an official U.S. visit regarded here as vitally important to the future of the Philippines, her controversial defense minister is the man she is leaving behind to mind the shop -- and the one everybody will be watching.

It was Enrile, a loyal supporter of Marcos for 20 years, who suddenly turned on the former president and launched the military revolt that brought Aquino to power in February. And it is Enrile who has since become the rallying figure for many of the Marcos loyalists who were politically orphaned by the deposed ruler's flight into exile and the breakup of his former political party, the New Society Movement.

Enrile -- "Johnny" to his friends -- is now the unofficial leader of the rejuvenated opposition Nacionalista Party, which has been busily organizing nationwide for local and congressional elections set for next year. Party officials say they want him as their candidate in the next presidential election in 1992.

A man who long has harbored presidential ambitions, Enrile, a 62-year-old Harvard-educated tax lawyer, currently is the odd man out in the Aquino Cabinet. As Marcos' defense minister for 16 years, and the administrator of martial law from 1972 to 1981, Enrile was responsible for issuing arrest warrants for some of the ministers who now sit in the Cabinet with him.

One of those arrested in the first hours of martial law was Benigno Aquino Jr., the late husband of President Aquino. For the seven years and seven months that the anti-Marcos senator was imprisoned in a military camp, it was Enrile whom Corazon Aquino had to visit to get permission to see her husband.

Benigno Aquino was assassinated by military men when he returned to Manila from three years of self-exile in the United States in 1983.

President Aquino now says she has gotten over the distrust she has long felt toward Enrile and the military. But the defense minister, who retained his position because of his leading role in the February "revolution" against Marcos, has become a target of communist rebels seeking a share of power in the new government. They have accused him of trying to sabotage cease-fire talks between themselves and the government.

Enrile has countered that he does not oppose the talks, but wants to expose what he calls the "tricky" terms the rebels advance. His stand has brought him into conflict with some of Aquino's advisers, and he has warned publicly that he is running out of patience and that he might react "like Rambo."

Behind the war of words, both sides also are apparently gathering ammunition for corruption charges with which to attack their adversaries.

One potential target of the Enrile camp, sources said, is Aquino's brother, Jose (Peping) Cojuangco, who is considered the eminence grise of the Aquino presidency. He is the leader of a left-of-center group, the PDP-Laban party.

For his part, Enrile is said to have become one of the Philippines' richest men during Marcos' 20-year rule. He was implicated in last year's "hidden wealth" scandal, where millions of dollars in government funds were used by officials and often hidden in foreign bank accounts or companies. Enrile owns property abroad. So far, however, the Presidential Commission on Good Government, charged with recovering the Marcoses' "ill-gotten" riches, has not dared to investigate him.

"Enrile feels that whatever role he played in the Marcos regime, he more than redeemed himself by his contribution to the incident that led to the regime's overthrow," said a fellow Cabinet minister.

Enrile has acknowledged that he owns a condominium in San Francisco that he said was purchased in the mid-1970s for $ 180,000. But he and his wife also reportedly have owned at least three San Francisco properties, one a $ 1.8 million mansion bought through a company called Renatsac.

Most of the controversy about Enrile's wealth, however, has centered on holdings in the Philippines. In 1979, a group of Filipino businessmen identified some of these alleged investments in a study entitled "Some Are Smarter Than Others" -- a reference to Imelda Marcos' famous explanation of her friends' and relatives' wealth. The main sources of Enrile's power and wealth, it said, were the logging and coconut industries.

Enrile used his powers as defense minister to "create a political monopoly over the logging and lumber industry," the report charged. "Clamping down on competitors as illegal loggers and controlling their production with the help of the military, and acquiring exclusive franchises and licenses for logging, Enrile has been so successful in his operations that he now owns at least seven lumber or wood-based companies."

With his close friend, Eduardo M. Cojuangco Jr., a longtime Marcos crony and cousin of President Aquino, Enrile was also involved in the United Coconut Planters Bank, which collected more than $ 1 billion in so-called levies from the country's 1.2 million coconut farmers over a nine-year period ending in 1982.

At the end of June, Enrile resigned as chairman of the bank, a post he had held for 11 years, after the Commission on Good Government sequestered 94.6 percent of the bank's stock. Earlier, he had reacted angrily when the commission sequestered a telecommunications company in which he had a financial stake and took control of the San Miguel Corp., a beer and food conglomerate that ranks as the Philippines' largest private company.

According to business sources and published reports, Enrile also owns a holding company, Jaka Investment Corp. (named after his children, Jackie and Katrina), a security agency called Sygma, a match company and a cacao plantation.