John R. Bolton, the U.S. ambassador to the United Nations, warned Tuesday that the United States might bypass the United Nations to solve some of the world's pressing problems if the organization is unable to make management changes that will make it more effective and prevent a recurrence of corruption.

Bolton's remarks come as the Bush administration is encountering stiff resistance from poor countries to United States-backed initiatives aimed at streamlining the United Nations' management practices. The influential Group of 77 developing nations recently issued a letter sharply criticizing plans by Secretary General Kofi Annan to establish an ethics office and to review General Assembly-created programs that are more than five years old to determine whether they should be shut down.

The dispute has underscored the Bush administration's inability thus far to parlay the findings of a U.N. investigation headed by former Federal Reserve chairman Paul A. Volcker into a catalyst for institutional change. Volcker's 18-month investigation into the United Nations' management of the $64 billion oil-for-food program in Iraq uncovered evidence of corruption by U.N. diplomats, foreign dignitaries and companies from more than 60 countries.

Bolton said the General Assembly has "essentially not made progress" since President Bush and other world leaders convened a U.N. summit in September to endorse a platform of changes, including proposals to increase scrutiny of spending practices and to create a human rights council that would exclude rights abusers. He said that continued resistance to change in the organization would drive the American public away from the United Nations.

"Americans are a very practical people, and they don't view the U.N. through theological lenses," Bolton told reporters outside the General Assembly hall. "They look at it as a competitor in the marketplace for global problem-solving, and if it's successful at solving problems, they'll be inclined to use it. If it's not successful at solving problems, they'll say, 'Are there other institutions?' . . . that's why making the U.N. stronger and more effective is a reform priority for us: Because if it's a more agile, effective organization, it is more likely to be a successful competitor as a global problem-solver."

World leaders had called on Annan to present a series of specific reform proposals to the 191-nation General Assembly in early 2006. But Bolton has voiced concern that key initiatives -- including the new ethics office, a human rights council and a peace-building commission -- would not get funded until the next budget negotiation cycle, in late 2007.

In an effort to prod states into action, Bolton proposed delaying the passage of the United Nations' $3.6 billion 2006-07 budget until the United States-backed reforms have been adopted. He suggested the General Assembly could pass a temporary budget to finance the organization's operations through the first three to four months of 2006.

Some U.N. delegates fear that the United States will use the maneuver to redirect funding from programs that are popular with diplomats from poor countries to initiatives the United States and its allies support.

Annan told reporters on Monday that he opposes a delay, warning that the failure to adopt the budget by Dec. 31 may "create a serious financial crisis for the organization."

Annan declined to comment on reports that Bolton warned that the United Nations could find itself sidelined if it fails to implement the administrative changes the United States supports. "I'm not the interpreter of Ambassador Bolton," he said.

Annan sought to allay suspicions by G77 members that the effort is aimed at reordering the United Nations' administrative priorities to serve American interests, and to transfer more control of the organization's budget from the General Assembly to the secretary general's office. "I made it quite clear that there's no attempt at power grab," he said. "We accept the General Assembly as the key deliberative body of the organization."

Ambassador John Bolton said the United Nations has made little progress on reforms.