Mulroney Boosted for Top U.N. Post : Diplomacy: He emerges as a leading candidate to succeed Perez de Cuellar, despite denials that he is seeking the job.

Prime Minister Brian Mulroney of Canada, an ebullient politician with more popularity abroad than at home, has quietly emerged this week as a leading candidate to succeed the retiring Javier Perez de Cuellar as secretary general of the United Nations.

Although Mulroney, 52, has denied that he is seeking the job, diplomats and bureaucrats have been talking of little else this week in the halls and lobbies of the U.N. headquarters in New York.

“I have been approached by tens of colleagues who have made it abundantly clear that they viewed his name as a very, very serious candidate,” said L. Yves Fortier, Canada’s ambassador to the United Nations. “When I say that he is not a candidate, many say that maybe he will change his mind.”

The focus on Mulroney reflects a feeling among many governments that the United Nations, finally back in the limelight of world consciousness, badly needs a high-profile leader with proven skills at public relations and administration--skills lacking in Perez de Cuellar, a soft-spoken, longtime Peruvian diplomat.

In the last few years, the world body has attracted increasing attention as a new mood of cooperation between the Soviet Union and the United States broke the long paralysis of the international organization. The Persian Gulf War in particular made it clear that the United Nations could play a significant role in international crises.

It is widely assumed here that Mulroney is the personal choice of President Bush, but this has not been confirmed. When asked in Washington if the United States had a preference, State Department spokesman Richard Boucher replied: “We do not discuss the sensitive issue of secretary general candidacies in public.”

The selection process by the Security Council is complex and secretive, and there are numerous potential complications for Mulroney. Moreover, the council already has 13 other names before it and could add more at any time.

If the council does not name Mulroney, most analysts expect it to choose either Egyptian Deputy Prime Minister Butros Butros Ghali; U.N. civil servant Prince Sadruddin Aga Khan, an Iranian citizen who was born in France, or Zimbabwe Finance Minister Bernard Chidzero.

A Mulroney candidacy faces two key obstacles: a demand by African states that the council name an African for the first time to the post and the expressed preference of China for a candidate from the Third World. China’s mood is especially important since it has a veto in the Security Council.

Two anonymous ambassadors--many diplomats believe they were American and British--put Mulroney’s name on the list Monday. There are complications involving any support from the United States. Many Third World delegates, fearing that Bush intends to use the United Nations as an instrument for imposing his vague “new world order,” might be suspicious of a secretary general viewed as beholden to the President or close to him.

On the other hand, Canada maintains extensive foreign aid programs in the developing countries, and Mulroney has made an impression in the Third World over the years by leading the battle within the British Commonwealth for sanctions against South Africa.

Under the U.N. Charter, the 15 members of the Security Council nominate a secretary general for ratification by a two-thirds vote of the General Assembly.

Members of the Security Council have said that they intend to make their choice in plenty of time for the new candidate to prepare to take over the job when Perez de Cuellar, 71, retires at year’s end. The best guess now is that a decision will be made in early or mid-November.

The real choice will likely be made by the five permanent members of the Security Council meeting privately, since all five--the United States, the Soviet Union, China, France and Britain--have the power of veto.

Soon after Mulroney’s name was entered, the prime minister, a Quebecer who speaks English and French fluently, denied that he is looking for the job.

Nevertheless, polls have shown that Mulroney’s Progressive Conservative Party now trails both the Liberal Party and the New Democratic Party and is likely to lose the next elections, due before the fall of 1993. Weakened by a recession, dissatisfaction over the U.S.-Canadian free trade agreement and the flare-up of bad feelings between English-speaking and French-speaking Canada, Mulroney’s popularity has sunk dramatically.