Manila — The list of potential successors to President Marcos, at least within the ranks of those who might be acceptable to the President, is constantly changing. At the moment, the name of constitutional lawyer Arturo Tolentino is often mentioned, though he has no power base and denies any presidential ambitions. Other major figures, like Defense Minister Juan Ponce Enrile, have lost power struggles this year and faded from view. Below is a quick look at four possible candidates.
''It's tragic,'' said an intimate of the President. ''He made her politically , but he can't unmake her.''
Like many observers, this person gives Mrs. Marcos most of the credit for her husband's presidential victory in 1965.
''She was absolutely tireless. She organized the campaign, helped with speeches, did everything.'' But, he also says, she is ''totally irrational.'' Critics call her ''ruthless'' and ''rapacious.''
A member of the powerful Romualdez family from the Visaya islands, Mrs. Marcos is steeped in politics: She even met her future husband in Congress.
She kept her own political ambitions sublimated until 1975. Then she became governor of Metro-Manila, the first of many positions that now include membership in the National Assembly and Minister of Human Settlements. Her assumption of most of these positions has been preceeded by expressions of reluctance and a large scale campaign urging her to take the job.
Most of these campaigns have been organized by her brother Benjamin ''Kokoy'' Romualdez, himself a member of the so-called ''Cordon Sanitaire'' that allegedly exercises a disproportionate amount of influence over the ailing President these days. It was Kokoy who organized the popular campaign that almost resulted in Mrs. Marcos becoming prime minister in 1981.
She apparently did her best to stop Benigno Aquino from returning to the Philippines. Not only did she twice reportedly warn another opposition leader that Aquino might be killed if he returned, but she allegedly offered Aquino financial help in the range of $3 million to stay in the United States.
Few doubt that Mrs. Marcos, who is in her mid-fifties, will make a play for power when the President leaves office. Many feel the President is supporting her in this, as a way to protect their family both physically and financially from reprisals by their many enemies.
Judgments about whether she will succeed are evenly divided.
''The Army won't let her take over,'' said a person close to the President.
Others feel the chief of staff and military strong man, Gen. Fabian Ver, may find it in his interest to work with the First Lady, if he could maintain military support for her.
Eduardo ''Danding'' Cojuangco.
He is a redoubtable force whether he runs for office or not.
A friend of his says that ''ruthless'' is a fair description of the man. He is also very rich.
A close friend of Marcos for years, Mr. Cojuangco's already substantial fortune has ballooned under the Marcos presidency. One prominent businessman now reckons he is worth ''hundreds of millions of dollars - the richest man in the country after the first couple.''
Mr. Cojuangco is best known for his virtual control of the coconut industry. He has benefited in particular from a tax levied on coconut planters, which is deposited interest free in the United Coconut Planters' Bank of which he is president and 10 percent shareholder. (Conjuangco arranged purchase of the bank from members of his own family in the mid-1970s when, under martial law, certain business groups not aligned with the Marcoses were forced to relinquish their holdings. By the end of 1981 the bank was estimated to hold nine billion pesos in levies - more than $1 billion at prevailing rates.
Late that year, Emmanuel Pelaez, a ranking leader of the KBL (Tagalog initials for Marcos's political party, the New Society Movement) and a coconut planter, organized a vigorous campaign against the levy. He was ambushed near his home and almost killed.
Cojuangco's critics - who are numerous, but generally tight-lipped - claim that he has channeled some of his fortune into the creation of a 1,000-man private army, scattered around his estates in Central Luzon, the Visayas, and Palawan island.
''These aren't just your usual New Society gunmen,'' said one retired senior general. ''He has hired some of the best soldiers in the country.''
He is also frequently alleged to have a large number of retired and active duty generals on his payroll. In addition to being KBL boss of Central Luzon, he also enjoys what one minister calls ''unofficial military suzerainty'' of the area.
A former governor and congressman from the same province as Benigno Aquino, Cojuangco is expected to make a bid for the presidency at some point, but is said not to have decided when. He suffers from one major disadvantage: persistent rumors that he was involved in the Aquino murder. Although a first cousin of Mrs. Aquino, he and Aquino were bitter political enemies.
His close relationship with Defense Minister Enrile faded earlier this year when the minister went into political eclipse. He is said by some observers to be on good with terms General Ver.
People are less sure about his relationship with Mrs. Marcos. Some observers say he has established a working relationship with her.
Others say the two detest each other: ''When Marcos goes,'' says one of the latter, ''they'll come out of their corners fighting.''
When Virata was appointed prime minister in 1981, his reluctance was unfeigned. Now, two years later, he still appears ill at ease in his job.
The technocrat, with an masters degree in business from the Wharton School of Economics in Philadelphia, is the antithesis of the average New Society politician. He seems oblivious to the rhetorical flourish and the fine art of pork-barrel politics. In public speaking, he gives a deadpan, expressionless recitation of facts. He still seems nervous when he speaks in public.
It is this air of a backroom boy pushed unwillingly out front that appeals to his supporters. Top businessmen who have known him for years are convinced of his integrity and say that he fought hard against some of the more disastrous policies adopted by the government. Executives in the international financial institutions like him: he speaks their language and understands their ways of working.
And the American embassy here seems to feel comfortable with him: his analysis of the situation and prescription for recovery bear a striking similarity to those of Ambassador Michael Armacost.
These qualities and friendships may be his downfall. He has no known power base in the KBL. He is roundly disliked by Imelda Marcos and the President's business friends. When Mr. Marcos goes, the different warring KBL factions might well bury their differences temporarily to destroy Virata.
Virata might survive at the top with strong military backing. Some of his supporters are already thinking of an alliance between him and General Fidel Ramos, deputy chief of staff and the officer sometimes viewed as Virata's military equivalent - the apolitical professional. The idea still seems to be at the stage of boardroom pipedreams, though.
The chances of a non-KBL successor to the President are slim, but Mr. Zobel would definitely be one of the main outsiders in contention. He is another of the Philippines' richest men, and Zobel's headquarters in Manila's business district have become the focal point for business community's anti-Marcos demonstrations.
In fact, Zobel stands above the political spectrum. A friend of Marcos, he also was close to Aquino. He acted as go-between for the two men when Aquino was negotiating his return. More recently he was a go-between when Marcos tried to induce a southern opposition leader to join the Aquino assassination investigation board.
Since the assassination he has been quietly encouraged to become involved in politics. The business community would apparently support him. So, Zobel's supporters believe, would the Americans.
US Ambassador Armacost has discussed the idea with Zobel recently. Reports of their conversation vary: some say the ambassador merely sounded Zobel out on rumors that he was planning to go into politics. Others say that Zobel was subtly encouraged to do so.
Zobel is probably intrigued by the idea, but may doubt his ability to gain wide support. ''If he was offered the presidency, I think he'd take it,'' said someone who knows Zobel well. ''I'm not sure that he'd fight for it.''