As the State Department prepares to take over representing the United States in Iraq after June 30, it also wants to take over an independent inspector general's office charged with monitoring the spending of $18.4 billion in U.S. money earmarked for rebuilding the country.

When Congress passed the appropriation for Iraq reconstruction last fall, it included a separate inspector general's office at the Coalition Provisional Authority, the U.S.-led authority running the country, to conduct audits and investigations of the largest rebuilding effort since World War II. Stuart W. Bowen Jr., a Washington lawyer, was appointed inspector general.

In a June 11 letter to the Office of Management and Budget, the State Department proposed absorbing Bowen's office, its $75 million budget and responsibility for tracking spending on infrastructure projects in Iraq. A State Department official yesterday said the department could provide better oversight by integrating the functions of the new office into its own inspector general system.

Three Democratic senators -- Patrick J. Leahy of Vermont, Robert C. Byrd of West Virginia and Russell Feingold of Wisconsin -- expressed concern that the State Department would not be as determined as the independent inspector general in rooting out fraud and waste, leading to less oversight at a crucial time. Feingold, a sponsor of the provision creating the CPA's inspector general, said in a written statement that he is offering an amendment that would maintain the independence of the office and continue its operation until after most of the money for reconstruction has been allocated.

"It defies logic that the State Department is now proposing to weaken the one entity that Congress specifically tasked with keeping track of these tax dollars. Their plan could undermine the independence of this Inspector General and disrupt this important work, reducing Congress's ability to effectively account for these funds. It's unlocking the vault to those who want to cheat us," Leahy, senior Democrat on the Senate committee that funds foreign aid, said in a written statement.

"We created a special Inspector General because we need one entity on the ground in Iraq, exclusively focused on overseeing the spending of U.S. taxpayer dollars for reconstruction," Feingold said. "If we let this office dissolve, we are returning to business as usual, and we will actually be choosing to have less oversight than we have right now. That would be bad for the American taxpayer and bad for the reconstruction effort."

A variety of government organizations have been trying to examine U.S. spending in Iraq, including the General Accounting Office and inspectors general and auditors from the Defense Department and the U.S. Agency for International Development.

Bowen's office began operating in February with just a few people. It now has about 60 staff members, including about 20 auditors and investigators in Iraq. Spokesman Jim Mitchell said the office is conducting nearly two dozen audits and investigations and will issue as many as a dozen audit reports in the coming weeks. One of the subjects is the services provided by Halliburton Co. subsidiary KBR, he said.

Mitchell declined to discuss the office's future. "We'll let our audits and investigations speak for themselves," he said. "We have a very talented force of investigators and auditors on the ground in Iraq to make sure the interests of the American people are maintained."