As the Senate opened a new debate on the conflict, one of the president's staunchest supporters bluntly said the administration had pursued the wrong policy for years after toppling Saddam Hussein from power. "The strategy we had before was not the right strategy," said Christopher Bond, R-Mo. "We should have had a counterinsurgency strategy."

Asked later who bore responsibility for the error, Bond said, "Ultimately, obviously the president."

Democrats said Bush's newest strategy was hardly a success, either.

Senate Majority Leader Harry Reid, D-Nev., said that since Bush ordered thousands more troops to Iraq last winter, "We've lost more than 600 troops, costing the American taxpayers more than $60 billion. The escalation has done nothing to bring the Iraqi government together. It's done absolutely nothing to lessen the violence in Iraq."

Two Democrats, Sens. Carl Levin of Michigan and Jack Reed of Rhode Island, back legislation to require a troop withdrawal to begin within 120 days, to be completed by the end of April 2008.

A vote is expected next week, and Reid said nearly all Democrats support the proposal. Republican Gordon Smith of Oregon is a supporter, as well, and Olympia Snowe, R-Maine, told reporters during the day she may switch her position and vote for it, too.

Even so, the proposal appears to be short of the 60 votes needed to overcome a threatened Republican filibuster.

Despite a steady procession of Republicans calling for a change in course, several GOP lawmakers warned against a precipitous withdrawal.

"I believe that our military in cooperation with our Iraqi security forces are making progress in a number of areas," said Sen. John McCain, R-Ariz., who recently returned from his sixth trip to the region. He noted a dramatic drop in attacks in Ramadi in the western Anbar province.

Sen. Lindsey Graham, R-S.C., who accompanied McCain to Iraq, also cited progress since Gen. David Petraeus took command several months ago and the additional troops began arriving.

The Iraqis are "rejecting al-Qaida at every turn. I don't want the Congress to be the cavalry for al-Qaida," he said.

Graham was also part of a group of senators who met privately during the day with Stephen Hadley, the president's national security adviser, and Lt. Gen. Douglas Lute, a top adviser on the wars in Iraq and Afghanistan. The senator said afterward the White House is looking at new ways to hasten progress in two primary areas: destroying al-Qaida in Iraq and forcing the U.S.-backed government in Baghdad to make political progress.

But he quoted Bush's aides as saying the administration would oppose calls for a troop withdrawal.

Bush was in Cleveland during the day, and he said issues related to troop strength "will be decided by our commanders on the ground, not by political figures in Washington, D.C."

He added, "I call upon the United States Congress to give General David Petraeus a chance to come back and tell us whether his strategy is working, and then we can work together on a way forward."

Petraeus is expected to make his report in September, but Bush also must give Congress an evaluation by July 15 on the progress made by the government of Nouri al-Maliki in several areas of political and economic change.

State Department spokesman Sean McCormack declined to list any benchmarks that have been met. But he conceded that the most prominent goals had not ¡ª enactment of legislation to allocate oil and gas revenue among the Iraqis or a law to address consequences of the mass firings of Baath Party members.

The report is also expected to say that the Iraqi government has made progress in other areas, including tamping down violence in Anbar province.

Bush's allies made clear their unhappiness with the government in Iraq.

"The central government's dysfunction is real. I'm not here to say that it's not," said Graham. "I am in many ways more depressed than I've ever been about political reconciliation in the short term."

McCain, Graham, Bond and others took turns on the Senate floor during the day to warn of grave consequences if Democrats get their wish for a quick troop withdrawal.

At an afternoon news conference, Bond also brought up the question of overall strategy.

"Late last winter we confirmed General Petraeus unanimously to bring a new strategy. Republicans and Democrats said we needed a new strategy, and there's no question we did.

"The strategy we had before was not the right strategy. We should have had a counterinsurgency strategy. Unfortunately, General Garner lost that argument several years ago," he said a reference to the general who was installed as the first postwar governor of Iraq. Garner arrived in Iraq in April 2003, and was replaced the following month.

Asked, in retrospect, how long the House and Senate should have permitted an inadequate strategy to continue, Bond replied, "Congress was not running the war."

While Democrats have cast their legislation as a plan to withdraw troops, it envisions a force remaining to fight terrorists, protect U.S. property and train Iraqi troops. Reid told reporters he did not know how many thousand troops would be required.