The Bush administration told Congress on Wednesday it opposes a bill to overhaul the way the United Nations works, citing a requirement the U.S. withhold dues if the organization fails to make changes.

The bill, sponsored by Rep. Henry Hyde (search), chairman of the House International Relations Committee, was to be debated by the House on Thursday.

Hyde, R-Ill., said he was not surprised by the administration opposition, but promised to push back.

"The Constitution gives to Congress the power of the purse," he said in a statement. "We intend to exercise it in pursuit of meaningful U.N. reform."

Hyde's bill would require the U.S. to withhold up to 50 percent of U.S. dues if the United Nations (search) failed to put in place specific changes.

Hyde argues that the threat of losing dues would be the only way to get the changes. President Bush already had indicated he did not want the dues provision to be include in final legislation.

The largest financial contributor to the United Nations, the U.S. pays about 22 percent of the annual $2 billion general budget.

Senior State Department officials telephoned word of the official position to committee staff members Wednesday, an aide to Hyde said. White House press secretary Scott McClellan and State Department spokesman Sean McCormack both said an official position on the bill would be announced soon.

"The president has repeatedly called for significant reform of the U.N. and stated his support for many of the reforms contained in this bill," Hyde said.

"The principal area of disagreement concerns the provision in its current form that mandates withholding U.S. dues. This is not surprising," Hyde said. "Every administration reflexively resists congressional involvement in foreign policy and opposes any limits on its freedom of action."

Rep. Tom Lantos, senior Democrat on House committee, hoped the administration's notification would have an effect.

"A better alternative would be to give the administration the option to decide whether and when U.S. financial support ... should be withdrawn, and by how much," Lantos, D-Calif., said in a statement. "Democrats have offered such an alternative."

Lantos has offered a bill that would give the president a waiver over withholding of the dues.

The government fell millions of dollars into arrears in the late 1990s because an earlier fight between White House and Congress. As a result, the U.S. almost lost its voting rights in the U.N. General Assembly.

Hyde's bill followed reports of numerous problems within the U.N. organization in recent years. Chief among the was the oil-for-food program in Iraq. It was designed to minimize the effect on civilians of continuing penalties against then-President Saddam Hussein's government.