Defense Secretary Robert Gates urged Congress to approve additional war funding by July 4 or risk forcing the Pentagon to curtail defense operations.
Gates told Senate appropriators he is "becoming increasingly concerned" by the delay in the approval of a $33 billion war supplemental for the remainder of this fiscal year.
The Senate has approved its version of the supplemental but the House has yet to act.
If Congress does not approve the funding by July 4, he warned, the Pentagon would have to start scaling back defense operations.
Gates's plea comes as both Democrats and Republicans have expressed serious concerns about the U.S. mission in Afghanistan after a series of setbacks, particularly in the southern part of the country.
Pentagon and military officials this week have been trying to allay congressional concerns over Afghanistan and retain support for the president's strategy as part of a number of congressional hearings in both the Senate and the House.