United Nations Ambassador John Bolton (search) told Congress Tuesday that he's working hard to press the U.S. case for an urgent overhaul of the world body, but he expects a tough diplomatic campaign to win the necessary support.

Making his first appearance before the Senate Foreign Relations Committee since President Bush (search) used recess-appointment to install him over the objections of Senate Democrats, Bolton said he has been engaged in "a matter of intense diplomacy in New York" to try to rally support for changing the U.N.

Bolton said that while rich countries like Japan, Britain and others in Western Europe support the U.S. proposals, the trick will be to get developing countries, which are needed to reach a consensus, on board. He said he has met with 70 of the organization's 191 member states.

"This cannot be seen as simply an American initiative," Bolton said. "This is going to take a sustained diplomatic campaign, not only in the United Nations but in capitals" of U.N. member countries, he added.

Bolton testified before the committee that refused to endorse him as Bush's ambassador; Bush bypassed the Senate during its midyear recess and appointed Bolton anyway.

Bolton told the committee that many changes were needed at the United Nations, including a way to fix a discredited human rights commission that he said routinely had as members such countries as Cuba and Zimbabwe, despite their frequent rights abuses.

But, Bolton said, it will take time to complete the overhaul.

"We're not going to declare victory after a few cosmetic changes," he said. "Reform at the United Nations is not a one-night stand. Reform is forever."

Paul Volcker (search), head of a panel that investigated corruption in the U.N. oil-for-food program in Iraq, testified earlier that a primary panel proposal — creation of a chief operating officer at the world body — could create tensions with the secretary-general.

Volcker also said such conflicts could improve operations at the world body. "There could be some kind of a tension at times, but that could be healthy," said Volcker, former chairman of the Federal Reserve Board.

The operating officer would be subordinate to the secretary-general but would have broad powers over finances and other elements of the organization's operations.

The chief operating officer proposal was intended by the three-member panel to insulate U.N. administrators from political pressures faced by the secretary-general. The panel's report said the chief operating officer could ensure that hiring decisions were based on talent rather than "political convenience."

The yearlong investigation by Volcker's panel sharply criticized top U.N. leaders and said they tolerated corruption and allowed Saddam Hussein's government to pocket $10.2 billion through the oil-for-food program and other illegal oil sales. The program was intended to allow Saddam's government to sell oil and use the proceeds to pay for food and other humanitarian items while Iraq was under international sanctions.

At the hearing, Volcker was reluctant to endorse a suggestion by one of the main congressional critics of the United Nations, Sen. Norm Coleman (search), R-Minn., that a "culture of corruption" was tolerated there.

"It certainly had a culture of inaction, let sleeping dogs lie, let's not push too strongly for finding out areas of potential corruption," Volcker said.

Meanwhile, Secretary of State Condoleezza Rice (search) huddled with U.N. Secretary-General Kofi Annan during a surprise trip to New York for a breakfast meeting to brief him on her discussions in Europe on Iraq, Iran, Syria and Lebanon, Sudan and other issues, State Department spokesman Sean McCormack said.

"This was an opportunity to compare notes," on Rice's consultations and on Annan's recent trip to Latin America, McCormack said.

In his opening statement at the hearing, committee Chairman Richard Lugar (search), R-Ind., urged Annan to put before the U.N. General Assembly quickly a blueprint for action on changes necessary for the world body.

Lugar said the United States should help bring the reform proposals forward and decide what to do if this did not happen. He said a document that the General Assembly approved in September on reform lacks details necessary to be a blueprint for action.

Instead, he said, it asks the secretary-general to submit proposals to the General Assembly for further negotiation and approval.