The US administration is to face pressure from two senators to make the contract bidding process in Iraq come under closer scrutiny.
Halliburton won the contract to restore Iraq's oil supply
A Republican and Democrat have joined forces to propose a bill to either make the system more competitive, or more clearly justified if open bidding does not take place.
In the past there has been criticism over the way the Bush administration has allocated work in the restoration of the Gulf state.
In particular there has been anger that engineering contracts have gone to companies close to members of the Bush administration without being opened to a public tendering process.
One contract, to restore the country's oil supply has gone to a subsidiary of Halliburton, the company run by Vice-President Dick Cheney before he took office.
Mr Cheney - a chief executive of Halliburton from 1995 to 2000 - has strongly rejected any suggestion that the company's close ties to the administration helped secure the work.
In addition, the largest construction contract, for more than $600m, went to Bechtel without an open, competitive process.
The BBC's North America business correspondent Stephen Evans said the administration argued that speed was crucial and Bechtel's engineering track record was renowned for being second to none.
Republican Senator Susan Collins and the Democrat Ron Wyden are jointly sponsoring a bill to make the way future contracts are allocated much more transparent.
The two politicians say their suggestion - coupled with President Bush's request for $87bn to be spent rebuilding Iraq - would demand more from bidders.
"The Iraqi contract process looks like Dodge City before
the Marshals showed up," Oregon Democrat Wyden told a news conference.
"It just doesn't pass the smell test to have companies not be part of the competitive bidding process."
Ms Collins said she did not know whether existing rules on
open contracting had been followed when Kellogg Brown & Root, a divison of Halliburton was awarded the Iraqi oil work.
The law on open bidding does allow some exceptions, Collins told news agency Reuters.
The proposal would mean that funds for Iraq would only be spent on competitive contracts, apart from situations where the awarding agency notified Congress and explained - in the official Federal Register - why an open competition was rejected.
Congress' watchdog, the General Accounting Office, is
conducting an in-depth review of contracts already awarded in
The Collins-Wyden amendment would only affect future contracts.