Paris ? In quieter times I once described Kofi Annan as a good man in a difficult job. That’s a vast understatement today. Greatness is required now from the secretary-general if he is to rescue the United Nations from mounting threats to its reputation and effectiveness.

The most immediate peril to the U.N.’s good name rises from the scandal engulfing its oil-for-food program, which was long used by Iraq’s Baathist regime to extort kickbacks from international oil traders. Those under-the-table payoffs helped Saddam Hussein break sanctions, fund weapons programs and build those obscenely gaudy palaces.

Whether U.N. personnel were directly involved in the corruption is a matter of dispute and of investigation. But the mechanics of the payoff scheme have been stripped bare in Baathist files uncovered in Baghdad by the Iraqi National Congress. Rep. Christopher Shays is conducting a House subcommittee inquiry and will hold hearings later this week.

Clearing up what is becoming known as the oil-for-fraud fiasco is essential to Annan’s larger task of rebuilding the shattered trust between his organization and its most important partner, the United States. The burden of finding a new balance in global cooperation does not lie only with the Bush administration or its successor. It takes at least two to multilateral, as the old saying almost goes.

Annan obviously has a major role in any new effort to redefine multilateralism for the 21st century. He is trying to get the U.N. involved in Iraq without getting the U.N. too involved in Iraq. He takes care at the same time not to get dragged into U.S. election-year politics, where the U.N.’s capabilities and value system are becoming a major issue.

Defiance by North Korea and disrespect from Iran are undermining the world body’s nuclear non-proliferation regimes. The rapid reaction forces being established by NATO and the European Union could greatly reduce the scope of U.N. peacekeeping in Africa and Central Asia and thus make it a less useful tool of multilateralism.

Annan knows the strengths and weaknesses of the U.N. bureaucracy from the inside, having risen through its ranks to the top. The Ghanaian diplomat mixes steely integrity and great compassion in doing his job. In the oil-for-food investigation, he will need to show more steel, less compassion.

He cannot afford to allow any suspicion to linger that the secretariat he heads was complicit in a scheme that helped an outlaw nation defy the U.N.’s own sanctions and disarmament resolutions. Annan may not be able to track down illegal kickbacks the program facilitated — Shays’ inquiry or the aggressive forensic accountants the Iraqi Governing Council has hired may have better luck at that — but here are some of the institutional questions Annan’s own investigation must explore:

Why did the United Nations decide to deposit the oil-for-food billions in private interest-bearing bank accounts rather than take up in-house suggestions to use the World Bank, which has a reputation for efficiency and transparency in all phases of international finance?

How competitive were the interest rates these banks paid to the U.N.? Did U.N. staff members develop a vested interest in financing their own projects from the interest income the organization received? How did the U.N. react to complaints that humanitarian relief bought with the oil revenue was not distributed fairly — or at all?

In short: Does the record show that the U.N. understood and carried out its fiduciary responsibility to the people of Iraq?

Annan is painfully aware that he does not have the staff support or other resources needed to assume a sweeping mandate to run Iraq, as urged by John Kerry and his surrogates. They portray the world body as a readily available golden bridge of retreat for an orderly U.S. exit strategy.

Annan must walk a narrow line between not feeding unrealistic expectations and avoiding insulting the possible future in the person of Kerry. The Democrats should scale back rhetoric that claims or implies that a return to multilateralism will fix all.

The world body has endured enough damage from an administration that did not hide its skepticism and lack of good will. It does not need to be set up for new failure by those who proclaim to be friends.

Jim Hoagland is a columnist for Washington Post Writers Group.