WASHINGTON -- Lawmakers say they will pursue a presidential commission designed to root out waste and fraud in military contracts despite President Bush's concerns that it could usurp his authority.

Bush signed into law on Monday a wide-ranging defense bill that includes instructions to create a commission to investigate defense contracts in Iraq and Afghanistan. It is modeled after a similar commission that was headed by Harry Truman in the 1940s to uncover abuse in military contracts during World War II.

Along with his signature, Bush singled out the commission and three other provisions that could "purport to impose requirements that could inhibit the president's ability to carry out his constitutional obligations."

A White House spokeswoman said parts of the contracting provision could be read to require the Justice Department to report whether or not they are prosecuting individuals.

"Under long-standing constitutional principles, the executive branch may protect from disclosure certain sensitive information, including national security information, as well as information about decisions whether to file criminal charges," spokeswoman Jeanie Mamo said yesterday. "The signing statement provides notice that the commission's requests for information, if they are too broad, may run afoul of the Constitution."

Such "signing statements" are controversial tools in which the president signs a bill into law but notes portions he may ignore.

House Speaker Nancy Pelosi, D-Calif., said Bush can't just pick and choose.

"His job, under the Constitution, is to faithfully execute the law -- every part of it -- and I expect him to do just that," she said.

Virginia Democratic Sen. Jim Webb, who sponsored the military contracting provision with fellow Democratic Sen. Claire McCaskill of Missouri, said Congress intends to move forward with setting up an eight-member commission.

Another section Bush targeted created a statute that forbids spending taxpayer money "to establish any military installation or base for the purpose of providing for the permanent stationing of United States Armed Forces in Iraq" or "to exercise United States control of the oil resources of Iraq."

The Bush administration is negotiating a long-term agreement with Iraqi Prime Minister Nouri al-Maliki. The agreement is to include the basing of U.S. troops in Iraq after 2008, as well as security guarantees and other economic and political ties between the United States and Iraq. Critics say the action could bind future presidents to continue with a troop presence in Iraq without congressional treaties.

Some legal specialists disagreed with the administration's legal theory.

"Congress clearly has the authority to enact this limitation of the expenditure of funds for permanent bases in Iraq," said Dawn Johnsen, an Indiana University law professor who was the head of the Justice Department's Office of Legal Counsel during the Clinton administration.