Bush is expected to veto the bill early next week. But bipartisan negotiations have already started on a compromise to cool the red-hot war debate, at least on the funding front.

Senate Minority Leader Mitch McConnell (R-Ky.) spoke with Bush yesterday morning and later held initial talks with Senate Majority Leader Harry M. Reid (D-Nev.). Senior Democratic and Republican lawmakers began to weigh alternatives to the legislation's most contentious provision, the binding withdrawal terms. The goal is to be more flexible but still restrain how Bush conducts the war.

Sen. John W. Warner (R-Va.), who has criticized Bush's war policy but opposed the Democratic bill as too heavy-handed, singled out one development that has stoked a more cooperative spirit on Capitol Hill: word that the Iraqi parliament may recess for two months this summer.

"That would send a very bad signal to the world that they don't have the resolve that matches the resolve of the brave troops that are fighting in the battle today," Warner said.

The provision most likely to survive the next round is a set of political and diplomatic benchmarks for the Iraqi government. The language all but certain to be dropped, or at least diluted, would require troop withdrawals to begin as early as July 1 and no later than Oct. 1. Another sticking point is the bill's $21 billion worth of domestic spending, which Bush and some Republicans have protested as pork.

A significant number of Republicans support the benchmarks — possibly enough to override a second veto, should Bush resort to that. The measures would prod Baghdad officials to build up military forces, crack down on militias and sectarian violence, protect minority rights and manage Iraq's extensive petroleum reserves.

Bush announced the benchmarks in January in a televised address but set no consequences if the Iraqis failed to deliver. The spending bill would make a continued U.S. troop commitment contingent on progress — although only up to a point.

Beginning July 1, if Bush decides that the Iraqis are falling short, U.S. combat forces would be withdrawn over six months. If the government shows progress, the deadline would be extended until Oct. 1, with troops leaving by March 2008.

GOP leaders signaled yesterday that they are ready to negotiate. In the House, which passed the measure late Wednesday largely along party lines, Minority Leader John A. Boehner (R-Ohio) said the veto "will give us a chance to sit down with our colleagues across the aisle and find common ground."

McConnell said, "There are a number of members . . . who do think that benchmarks could be helpful, depending upon how they're crafted."

Gen. David H. Petraeus, the top U.S. commander in Iraq, has been in Washington for the past several days briefing lawmakers as they voted on the spending package. He told reporters at the Pentagon yesterday that despite an increase in troop levels, the overall violence in Iraq has not declined, and he warned that U.S. casualties may increase in the coming months.

Because his plan to improve security in Baghdad moved soldiers from big bases to isolated outposts in the city, "this effort may get harder before it gets easier," he said. "It is an endeavor, again, that is going to require enormous commitment and commitment over time."

While a deadline for bringing the troops home would not survive a veto, the Democrats' legislative victory is significant, beating expectations on both sides of the aisle. But it also opens the door to complicated new challenges. House and Senate leaders must establish terms that are tough enough to satisfy a large antiwar faction, particularly in the House. At the same time, they must water down the bill to a point where Bush will sign it.

Bush, Vice President Cheney and other administration officials accuse Democrats of crass political posturing. White House spokeswoman Dana Perino called the spending bill "defeatist legislation" and reiterated Bush's pledge to veto it. But she added that the president "looks forward to working with congressional leaders to craft a bill that he can sign."

As the second phase of the spending debate unfolds, antiwar lawmakers are pressuring Democratic leaders to seek the most stringent terms possible. One idea is to pass a shorter-term funding bill — possibly in the $30 billion to $40 billion range — that would allow Congress to revisit the war in several months.

One champion of this approach is Rep. John P. Murtha (D-Pa.), a senior appropriator with strong military ties, who has emerged as one of Bush's strongest critics. Murtha is advocating a 60-day bill that would provide enough funds for operations, maintenance and personnel while carrying the current legislation's provisions on benchmarks and readiness standards for deploying troops.

Senate Democrats worry that a shorter duration would be impractical. But yesterday, Reid confirmed that it was in the mix. "We have a lot of things we'll look at — that's one of the things," he said.

Democratic leaders expect the negotiations on a new bill to run at least through mid-May. Although Bush has demanded the money as soon as possible, a report last month from the Congressional Research Service found that the Army has adequate funding to carry it through the end of July.

Under other alternatives, the toughest provisions of the war funding bill would shift to a defense policy bill that will come before the House next month, or would be broken out and beefed up in a separate bill in coming weeks. That would give antiwar liberals measures to vote on, while the Democratic leadership negotiates with Bush on war funding

The bulk of the spending package, about $95.5 billion, would go to the Pentagon for operations in Iraq and Afghanistan. But Democrats also included a minimum-wage increase that they have struggled to complete. They also added $21 billion for veterans' and children's health care, port security, avian flu research, drought relief for farmers and Katrina-related aid for the Gulf Coast.

Bush has repeatedly cited the domestic spending as one reason he would veto the bill. But some of the biggest provisions have powerful GOP defenders, including Senate Minority Whip Trent Lott and Sen. Thad Cochran, the ranking Republican on the Senate Appropriations Committee. Both senators represent Mississippi, which would benefit from nearly $7 billion in Katrina aid.