Despite the dire need for better health care, more electricity and clean water, a functioning sewage system and other services, the accountability office has previously estimated that Iraq spent only 22 percent of the oil money set aside for reconstruction in 2006. And in January, the office, which is charged with overseeing the Iraqi government’s finances, reported that Iraq had spent a meager 4.4 percent of its 2007 reconstruction budget by August of that year, the most recent figures available at the time.

As a result, the letter from the Armed Services Committee says, “we believe that it has been overwhelmingly U.S. taxpayer money that has funded Iraq reconstruction over the last five years, despite Iraq earning billions of dollars in oil revenue over that time period that have ended up in non-Iraqi banks.”

The letter was signed by Senator Carl Levin, the Michigan Democrat who is the committee chairman, and Senator John W. Warner, a Virginia Republican who is a former chairman. Senator John McCain of Arizona, the ranking Republican on the committee and the presumptive Republican nominee for president, did not sign the letter.

Iraqi officials say they face many obstacles in what might seem to be a straightforward task: spending their plentiful money. Workers are attacked, engineers and contracting experts have fled government ministries, construction companies refuse to take jobs in risky areas and building materials are not available.

And if all of those factors were not daunting enough, the various Iraqi and American government entities involved cannot even agree on how much the notoriously opaque Iraqi bureaucracy has in fact spent on reconstruction.