WASHINGTON — Saying that a bipartisan panel’s plan for a new Iraq war strategy “may be the last best chance to get it right,” Sen. Jack Reed called on President Bush yesterday to use the blueprint to help bring stability to the embattled nation.

Reed praised the Iraq Study Group for what he called “a significant contribution” to the debate on the war and argued that its recommendations are “strikingly similar” to those of a Democratic Senate resolution that he coauthored last summer with Michigan Sen. Carl Levin.

Reed summed up the common ground between his resolution and the study commission this way: “focusing on redeployment of American forces; active diplomacy; helping to enhance the security forces of the Iraqi government; and calling upon the Iraqi government to take those political steps that are necessary to make progress.”

Sen. Lincoln D. Chafee applauded the commission’s call for a comprehensive diplomatic effort that would involve Iraq’s neighbors — including Iran and Syria — and would also seek peace between Israel and its Arab neighbors.

But Chafee, the only Republican senator who opposed the U.S. invasion of Iraq in 2003, said the challenge of improving the situation in the war-torn nation is “daunting.”

Chafee said Iraq has become so “chaotic” that the commission’s recommendations — including a mixture of incentives and sanctions to prod the Iraqi government to action — may fail.

Representatives Patrick J. Kennedy and James R. Langevin expressed concern that the commission report does not call for the withdrawal of American troops soon enough. But both Democrats said they support the commission’s call for U.S. troops to shift from a combat to a training and logistical role.

Langevin said the withdrawal of U.S. troops from Iraq “needs to start now.” He said, however, that he would defer to the judgment of U.S. military commanders.

The commission, led by former Secretary of State James A. Baker III, a Republican, and former Indiana Rep. Lee Hamilton, a Democrat, said all American combat troops could be removed by April 2008, leaving an unspecified number of troops to help train Iraqi forces and to serve various support functions.

But the report sets no firm deadlines and makes no specific recommendation for how many American troops should remain in Iraq, or for how long.

“The administration has to decide whether to stay there or get out,” said Kennedy, a onetime supporter of the war who has come to oppose it. “I’d like to get out.”

Kennedy also expressed doubts about the commission’s call for the United States to insist that Iraq’s government attain certain political, economic and military milestones. “Who decides whether the elections are democratic or whether oil is properly shared?” Kennedy asked.

Senator-elect Sheldon Whitehouse was not available for an interview, according to his office. But his office issued a printed statement in which Whitehouse praised the commission for its work and criticized what he called the Bush administration’s “disastrous failure.”

Reed, who will serve on the Armed Services Committee in the new Congress, with Levin as the new chairman, has met with the commission and its staff twice in recent months to give his views and recommendations. The former Army officer has made nine wartime visits to Iraq.

Reed said he thinks the report will win bipartisan support.

“Now it is up to the president” to use the paper “to forge a new policy, a new way forward that will help stabilize Iraq, and help us, as quickly as possible, redeploy our forces from Iraq.”

But Reed reiterated his opposition — shared by the authors of the report — to hard deadlines for withdrawal or specific prescriptions for troop strength.

He endorsed the commission’s call for U.S. combat troops to give way gradually to troops with training and logistical assignments. Reed said it will be easier to keep such troops safe than it is to protect combat troops but he acknowledged that tens of thousands of American service personnel would remain in Iraq for an indeterminate period of time under the Baker-Hamilton proposals.

Reed said he was particularly encouraged by the commission’s detailed listing of milestones that the Iraqi government should meet, as a condition for continuing American support.

The commission said the United States should spend as much as $5 billion a year to help Iraq meet its milestones for economic rebuilding, for improving its armed forces, and for reconciliation among its competing religious and ethnic groups. But the report also said that such aid — as well as military support — should be contingent on Iraqi progress toward the milestones.

“It is a carrot-and-stick approach,” Reed said. The report echoes several items on Reed’s longstanding list of actions that the Iraqi government should take, including the institution of provincial elections, fair distribution of oil resources and the dismantling of militias.

The commission’s call for diplomacy is “long overdue,” said Chafee, who lost his bid for reelection last month. Chafee, a member of the Senate Foreign Relations Committee, noted that he has spoken out in favor of negotiations with Iraq’s neighbors for several years.

More generally, Chafee said he is “willing to endorse any change in direction that is crafted in a consensual way.” He said the study group’s report appears to have been fashioned in a bipartisan manner.

Chafee expressed doubts about a key element of the report that Reed strongly endorsed. That was its suggestion that the United States cut support for Iraq if the Iraqi government fails to make progress toward the milestones.

“I wish I could be more confident that that would work,” Chafee said, “that with the stick and carrot we’ll get some results. The chaos is so deep that it is not so easy.”

Ultimately, Chafee suggested, Mr. Bush is responsible for testing the usefulness of the commission’s recommendations.

“The big question,” according to Chafee, is this: “Is the administration going to pay any heed” to the commission’s recommendations, “or is this just an irritation for them?”