The Army has warned program managers to prepare for a possible money crunch if President Bush vetoes an emergency war spending bill that calls for the eventual withdrawal of combat troops from Iraq.
But analysts say Pentagon staff will be the first to face cuts.
In a memo sent Monday, the Army Budget Office warned that a resolution to the standoff between Bush and Congress over the bill "is doubtful before the end of April."
It said managers needed to plan to stretch current funds into June, with operations in Iraq and Afghanistan exempt from the restrictions.
"The Army must take prudent action now within the limited flexibility available to the Army to extend the funding of mission essential services," the memo states.
The service bears much of the brunt of the wars in Iraq and Afghanistan, and Bush has asked for another $100 billion in military spending for those conflicts. Most of that money would go to Iraq, where the Pentagon estimates the cost of combat at about $2 billion a week.
But the president has threatened to veto any bill that includes a timetable for bringing the 4-year-old war to an end. Both the House and Senate have attached language calling for U.S. combat troops to leave Iraq in 2008 -- the House by the end of August, the Senate by March.
Bush told reporters Tuesday that the military would begin running short of funds in mid-April. But the independent Congressional Research Service concluded last week that the military will have the money to continue fighting through July without additional funding.
Bush has said the Democratic leadership of Congress would be to blame if he vetoes the bill.
Senate Majority Leader Harry Reid, a Nevada Democrat, accused Bush of "misleading" the public about the urgency of the situation, noting, "His own generals have said it that it will last until June."
Robert Maginnis, a retired Army lieutenant colonel, said a budget crunch could force troops now in the field to have their tours extended, since training for their replacements could be cut, while other units now at home could have to return to combat early.
Military analysts told CNN the first to feel a pinch will be workers at the Pentagon itself, where contract jobs, travel and other nonessential services would be slashed. But Maginnis said Bush's portrayal of units held over in the war zone was realistic.
Should cuts come, "We're going to cut back on training in this country, perhaps except those units that might be on their way immediately to the battlefield," he said.
Maginnis said the service may have to cut back on repairs to already-worn equipment. Army depots at home are already working "24-7" to recondition military equipment to go back, he said.
Other analysts -- retired officers who have dealt with past budget shortfalls -- told CNN that Bush's assertion that the Army would have to put off the formation of new brigade combat teams would be unlikely to happen immediately.
But they said a worst-case scenario eventually could see commanders without the fuel, ammunition or other supplies needed to pursue the enemy.
Under those conditions, American units would have to hunker down and wait for resupply -- or hand over more combat responsibilities to the Iraqi military and police.