In March, Secretary General Kofi Annan proposed the most far-reaching changes for the organization since its founding 60 years ago: reorganizing to combat terrorism and poverty, expanding the Security Council beyond the victors of World War II and setting new rules for the preemptive use of military force.

But six months of contentious negotiations by governments have stripped out many of the boldest initiatives, including proposals for creating 10 new Security Council seats. And delegates this week are straining to reach agreement on a far less ambitious package of steps that can be agreed on by some 170 leaders set to arrive in New York on Wednesday for a summit on U.N. reform.

Some key goals -- including the quest for agreement to condemn terrorists who target civilians or to establish a human-rights council that bars membership to rights abusers -- will be put off for discussion by the 191-member General Assembly after the summit ends Friday.

"When you get together with 191 countries to agree on substantive issues, it's obvious that you're going to end up with the least common denominator," Mauritius's U.N. ambassador Jagdish Koonjul said, after quarreling with U.S. negotiators over a proposed provision that would urge world leaders to support the International Criminal Court. "They said they would rather die than allow any reference to the letters ICC."

Annan's manifesto -- outlined in a document titled "In Larger Freedom" -- was designed to pump new life into multilateralism after the U.S.-led invasion in Iraq had highlighted a rift in international relations. But his effort to push through his changes have been hamstrung by corruption scandals that have weakened his authority. U.N. member governments, meanwhile, have been reluctant to make painful tradeoffs to achieve a bold reorganization of the global body.

Some officials now say that the goals were too grand for an organization whose members remain deeply divided over the nature of the world's problems. "If things collapse it will be because the traffic was too heavy for the road to bear," warned Munir Akram, Pakistan's U.N. ambassador, who played a pivotal role in blocking the enlargement of the 15-nation Security Council because its regional rival, India, aspired to a permanent seat on it.

This week's summit, which will draw the largest number of world leaders under one roof, was initially intended to review progress on commitments governments made in 2000 to fight grinding poverty and the spread of HIV/AIDS, malaria and other diseases that disproportionately strike the poor.

The summit's focus shifted following the Sept. 11, 2001, terrorist attacks and the invasion of Iraq. Abdallah Baali, Algeria's U.N. ambassador, said the summit was intended to strike a "grand bargain" between the world's poorest countries, who expected to get greater commitments of foreign aid, and the United States and other wealthy countries that wanted the United Nations to change its focus to address new security threats, primarily terrorism.

This meeting represents the first major test of U.S. diplomacy at the United Nations since President Bush bypassed the congressional confirmation process last month and installed John R. Bolton as U.S. ambassador through a 17-month recess appointment.

Since his arrival, Bolton has shaken up the negotiations on a document that can be agreed upon by leaders at the summit, introducing more than 750 amendments. The U.S. amendments called for eliminating new pledges of foreign aid to impoverished nations, scrapping provisions that call for action to halt climate change and deleting language urging nuclear powers to make greater progress in dismantling their nuclear arms.

Bolton has since struck a compromise that welcomes decisions by wealthy governments to increase foreign aid levels to 0.7 percent of their gross national products, but which does not say that governments must do so.

A small group of 15 key negotiators appointed by General Assembly President Jean Ping has also reached agreement in principle on provisions that would increase pressure on states to act to halt genocide, ethnic cleansing and other large-scale killings, and that would establish a peace-building commission to manage postwar recoveries. The negotiators have also agreed to condemn terrorism and set up a human rights council, although they would leave it to the General Assembly to later decide how to define terrorism and to work out the composition and mandate of the rights council.

But the negotiations remain deadlocked over several key issues, including provisions designed to hasten the pace of disarmament and halt the transfer of the world's deadliest weapons to terrorists. Negotiations are also stalled over measures aimed at ending trade subsidies by rich countries that hurt poor nations' ability to compete, and that would bring greater accountability and oversight to U.N. spending.

Bolton sought to dampen expectations that the agreement by world leaders would represent the kind of radical changes first envisioned by Annan. "This is a first step," he told reporters during a break in negotiations. He said the changes under negotiation "are important but I don't think even if they were adopted in full they would result in the kind of cultural revolution that we need in U.N. management and governance."

"Reform is not a one-night stand," he added. "Reform is forever."

The Bush administration has come under fire from other nations for opposing provisions that it feels would inhibit its ability to defend U.S. interests. The United States has firmly opposed a proposal by Annan to urge the Security Council to adopt a resolution setting guidelines for the use of military force.

The United States also has blocked regulation of small arms and has worked to eliminate references in a summit document to the obligations of nuclear weapons states, under the nuclear Non-Proliferation Treaty.

"What you see here is the U.S. carving out of this document any reference to the responsibility to the nuclear weapon states to eliminate their nuclear arsenals," said Daryl Kimball of the Arms Control Association. "And that is going to make it all the more difficult to strengthen an already beleaguered nuclear nonproliferation system because other states are less likely to foreclose their nuclear options if the United States and others continue to pursue theirs."

Human rights and development advocates, meanwhile, say that a number of other countries have quietly sought to undercut the negotiations. "Less than 48 hours from the beginning of the summit there remains real risk that major agreements will be blocked by a small number of countries that seem determined to block the summit's success," said Nicola Reindorp of Oxfam International. "These include Pakistan, Egypt, Iran, Syria, Venezuela and Cuba."

New York police patrol outside the United Nations before the start of this week's summit marking the world body's 60th anniversary.