WASHINGTON — Lieutenant General Douglas Lute, a skeptic of the troop increase in Iraq and President Bush’s choice to oversee the war, said withdrawing troops may pressure the Iraqi government to make needed changes.

Under questioning from the Senate Armed Services chairman, Senator Levin, General Lute said the Michigan Democrat may be correct in his long-held assertion that the Iraqi government will only work to end sectarian strife if it has to.

A withdrawal “ought to be considered,” General Lute, 54, said during the committee’s hearing in Washington on his nomination as a coordinator of war operations in Iraq and Afghanistan.

While praising General Lute’s qualifications, Mr. Levin said the new position had little authority, making it difficult for General Lute to be effective. Secretary of State Rice, a Bush confidante, has been unable to reshape the administration’s war policy, Mr. Levin said. “One has to wonder, how does one expect that General Lute can be more successful?”

Senator Reed, a Democrat of Rhode Island, told General Lute that, while he would support him, “I don’t think I’m doing you a favor” because he would be put in an “impossible situation.”

The committee’s Republicans offered a more optimistic assessment of the impact General Lute could have, although none said he could reverse the trend of deepening violence among Sunnis, Shiites, and Kurds and their anger at the American occupation.

Senator Warner, a Republican from Virginia, said the most important aspect of General Lute’s job would be to “give the president impartial, straightforward advice” on the conflicts in Iraq and Afghanistan.

Senator Clinton, a panel member and Democratic presidential candidate, said in an interview that General Lute will have difficulty penetrating “the closed circle of decision-makers in the White House.”

“They are impervious to evidence and arguments,” said Mrs. Clinton, a New York lawmaker.

General Lute is currently director of operations for the Joint Chiefs of Staff at the Defense Department, a position he’s held since September 2006. Before that, he served for 15 months as director of operations for the U.S. Central Command, which includes Afghanistan and Iraq. He was in charge of overseeing daily combat operations, taking reports from combat commanders and reporting directly to General John Abizaid, who then headed the command.

In his new position, General Lute would become an assistant to the president and deputy national security adviser for Iraq and Afghanistan. He would manage the administration’s strategies in both conflicts and coordinate the policies of U.S. government agencies with roles in both countries, including the Defense and State Departments.