WASHINGTON — Humvees deployed for operations without scheduled upgrades. Troops called to the front without proper training. Those are the kinds of consequences the Pentagon and military analysts are predicting if Congress passes a funding bill for the war with a timeline for withdrawal amounting to a poison pill that forces a presidential veto.

Yesterday both the Republican and Democratic leaders of the Senate promised to finish work before Friday on a supplemental bill to fund the war in Iraq and Afghanistan. Whatever funding bill emerges from the Senate, it will have to be reconciled with a House bill that appropriates $124 billion for the military and other projects, but sets August 31, 2008, as a deadline for when troops will have to leave the field with few exceptions.

With the president already promising to veto that kind of legislation, the Senate Republicans are already expecting a veto and plotting out how to get the president a troop funding bill without binding deadlines.

The scenario has military analysts here already predicting the consequences. “We are already halfway through the fiscal year, the administration is asking for more $100 billion, the amount for Iraq is $70 to $80 billion, and this is just through September,” a senior fellow at the center-left Brookings Institution, Michael O’Hanlon, said. “Even if we are spending money at $8 or $9 billion a month, some of those costs don’t have to be incurred right away. But the sheer magnitude, if they need that much more money to finish the fiscal year, the implications for the military would be fairly soon.”

A senior fellow at the conservative Heritage Foundation, Mackenzie Eaglen, said she believed the effect on training for future deployments would be the harshest consequence of a disruption of funds. “Even though training and readiness are harder to measure, particularly with a stressed force, which is what we have today, these kinds of things are arguably as important as ammo and vehicles,” she said.

Ms. Eaglen, who served in Secretary of Defense Rumsfeld’s office as well as serving as a military analyst for Senator Collins, a Republican of Maine, added, “The army would have to consider suspending guard and reserve training, which directly effects next year’s Iraq deployments. One of the harshest consequences of this could be the extension of many soldier tours in Iraq.” She also said the upgrade of military vehicles such as humvees could be affected if the war budget is squeezed.

A former spokesman for the Clinton administration’s National Security Council, Colonel P.J. Crowley, who is now a fellow at the Democratic-leaning Center for American Progress, conceded yesterday that the Pentagon would face some funding problems if a supplemental appropriations was not signed into law by April 15. “Will they stop feeding the troops?” Mr. Crowley asked. “Of course not. When you rob Peter to pay Paul, some things may not get done. They may eventually get done at a higher cost. If someone puts a hold on the supplemental budget indefinitely, it would have a deleterious impact on the margins. A timely consideration of the supplemental is necessary. It’s a legitimate point, but up to a point.”

Republicans in the Senate are already preparing the rhetorical ground against Democrats regarding the effects it would have on the troops if the timetable for withdrawal is attached. The Senate minority leader, Mitch McConnell, a Republican of Kentucky, yesterday asked, “Who loses out in this strange calculus? American soldiers and Marines deployed in Afghanistan and Iraq, and their worried families here at home.” He went on to say that the Secretary of Defense, Robert Gates, has already warned of the effects of a disruption in spending. “Delaying the approval of funds would slow the training of units already headed into Iraq and reduce the funds available for repairs to buildings and equipment,” Mr. McConnell said.

Mr. Gates told reporters March 22 that the kinds of cost saving the Pentagon would have to consider include “curtailing and suspending home station training for Reserve and Guard units,” “slowing the training of units slated to deploy next to Iraq and Afghanistan,” “cutting the funding for the upgrade or renovation of barracks and other facilities that support quality of life for troops and their families,” and “stopping the repair of equipment necessary to support pre-deployment training.”

A spokesman for Senate Majority Leader Reid, a Democrat of Nevada, said he did not think the withdrawal time lines are necessarily the “poison pill” Republicans insist they are. “The fact is the president does not need to force this confrontation,” James Manley said. “The Congress is going to continue to make sure he is held accountable for his flawed policies.”

Mr. O’Hanlon said he did not think Democrats would move away from their position on the time line. “There is too much group think in the Democratic Party right now. They are not doing their best thinking,” he said.