In an effort to address concerns in Washington, D.C., and New York that the price tag for the United Nations’ planned headquarters renovation is grossly inflated, Senator Coburn, a Republican of Oklahoma, has scheduled a hearing into the project for next week, Senate aides told The New York Sun. The star witness will be the developer Donald Trump, who has said the world body stands to waste hundreds of millions of dollars on the refurbishment.

The United Nations plans an overhaul of its Turtle Bay facilities, citing outdated equipment, unsafe working conditions, and security concerns as justification for the upgrade. U.N. officials estimate the price of the renovation – set to begin in 2007 and anticipated to take five years – at $1.2 billion. To finance the project, the Bush administration last fall offered a 30-year loan of $1.2 billion at 5.54% interest.

Although U.N. officials expected America, as host country, would lend the money interest-free, some members of the House and Senate have said even that offer is exceedingly freehanded and are demanding a more rigorous justification of the project, expressing concerns that American taxpayers – who shoulder 22% of U.N. operating costs – may be financing a boondoggle.

One is Dr. Coburn, a first-term Republican who is chairman of the Senate subcommittee on federal financial management, government information, and international security, part of the Senate Committee on Homeland Security and Governmental Affairs. In that capacity, Dr. Coburn investigates cases of waste and financial mismanagement at the federal level, and he has said America’s contributions to the U.N. renovation may qualify.

According to Senate aides, Dr. Coburn will demand an accounting of the U.N. refurbishment plans and expenditures before his subcommittee, in a hearing to be held July 21 at the Dirksen Senate building in Washington, D.C.

Aides said Dr. Coburn’s interest in the U.N. project was first piqued by the efforts of his Senate colleague Jeffrey Sessions, a Republican of Alabama, who introduced legislation in April that would halve the initial American loan offer and make the remainder contingent on sufficient transparency from the United Nations. Mr. Sessions, on the floor of the Senate, cited reporting by the Sun and statements by Mr. Trump in arguing that the projected cost of the U.N. refurbishment was several times the market rate for renovations in Manhattan and was “outrageous.”

Mr. Trump, whom Mr. Sessions invited to appear before the subcommittee, has also been a vocal critic of the world body’s construction plans. In February, the developer called the United Nations “a mess,” and in April discussed the renovation project at length with Mr. Sessions.

According to the Alabama senator, Mr. Trump met with U.N. Secretary-General Annan, at the request of a European diplomat, during the early stages of the renovation planning. He warned Mr. Annan that the $1.2 billion cost was exorbitant and could be the result only of “incompetence or theft.” Mr. Trump, according to Mr. Sessions, offered to manage the project and promised to complete it at a cost of $500 million, but never received a response from the world body.

“He shares my concerns about the enormous cost of the U.N. renovation project,” Mr. Sessions said in a statement, “and I look forward to having him share his expertise with Congress.”

One Coburn aide labeled Mr. Trump the “granddaddy of all real estate developers” and said Mr. Trump’s renown and expertise in large-scale New York construction made him an ideal witness. A spokeswoman for Mr. Trump confirmed yesterday that he would testify at the hearing, but said the developer was out of town and unavailable for comment.

Although the U.N. renovation has been reviewed by the Government Accountability Office, officials of the agency told the Sun in February that the GAO had signed off on the procedures the United Nations used to arrive at its cost estimates, but not on the estimates themselves. According to Dr. Coburn’s staff, requests made of the United Nations, the State Department, and the GAO for a detailed breakdown of the $1.2 billion – including plans for the construction – had yet to yield any information.

“Nobody has shown us anything,” one Coburn aide, who asked not to be named, said. “Senator Coburn just wants to know what’s inside – how many floors are being renovated, what type of renovation is going on each floor.”

“They’re asking the taxpayers to make this loan, and then pay ourselves back with interest as our contribution to the U.N. dues – so we want to know what’s going into that building,” the aide said.

Joining Mr. Trump in the effort to shed light on these questions will be Mr. Sessions and America’s acting ambassador to the United Nations, Anne Patterson. Another Oklahoma Republican highly critical of waste at the United Nations, Senator Inhofe, is also expected to testify.

Aides said Dr. Coburn’s hearing, in addition to trying to inspire the United Nations and organs of the federal government to be more forthcoming with information about the construction, will “lay a foundation for legislative action later.”

Dr. Coburn’s investigation would establish a recorded case history, aides said, so that those concerned about the excessive cost of the refurbishment could pursue a variety of tactics – perhaps reducing the amount of the loan appropriation in either the upcoming Foreign Operations Appropriation Bill or the Commerce, State, and Justice Bill, for example – if the Bush administration proves unwilling to detail to taxpayers how the $1.2 billion will be spent, and what kind of oversight the American government will have.

The United Nations hopes to find hundreds of thousands of square feet of office space for its staff to use during the renovation. A plan to build a “swing space” on a neighboring city park, and later for the consolidation of U.N. offices currently in rented space around the city, failed to win approval from the state Legislature last month. Those costs are not included in the $1.2 billion.

It remains unclear whether the United Nations will accept America’s loan offer, which expires September 30. Mr. Annan has recommended that the General Assembly accept the American offer, but representatives of several member states have professed profound dissatisfaction that America did not provide the loan interest-free and have urged the secretary-general to pursue alternative means of financing the project. The U.N.’s Fifth Committee, a budgetary arm of the General Assembly, is still debating whether to accept the loan.