The regulators are especially worried about trades used by banks or brokerage firms to move bonds off their balance sheets, which would remove the securities from the scrutiny of regulators who are trying to limit the overall surge in domestic credit.

WSJ: China Probe Focuses on Trading of Bonds

"The majority of senators believe the time is now to start drawing down U.S. forces, not just to pre-surge levels but beyond them, and to limit the mission of those remaining to fight al Qaeda, train Iraqis and help protect the borders, " he said.

CNN: 2008 politics woven through Iraq hearings