WASHINGTON (AP) – The top American commander in the Middle East warned Congress Wednesday against setting a timetable for the withdrawal of American troops from Iraq, saying it would impede commanders in managing American and Iraqi forces.

The assertion by Gen. John Abizaid seemed to put him at odds with some Democrats pressing the Bush administration to begin pulling out of Iraq.

Gen. Abizaid spoke as the Senate Armed Services Committee began re-examining American policy in the wake of last week’s Democratic election victory, which gave them control of Congress starting next year.

In arguing against a timetable for troop withdrawals, Gen. Abizaid told the committee that he and other American commanders need flexibility in managing American forces and determining how and when to pass on responsibility to Iraqi forces.

“Specific timetables limit that flexibility,” the general said.

Gen. Abizaid also said he believes American troop levels, now at about 141,000, should stay steady but may have to rise temporarily to train and advise Iraqi military units. No reductions are adviseable until the Iraqi security forces become more capable of dealing with the insurgency, securing Baghdad and dealing with the Shiite militia problem, he said.

“Our troop posture needs to stay where it is,” for the time being, he said.

Pressed by Senator Reed on how much time the American and Iraqi government have to reduce the violence in Baghdad before it spirals beyond control, Gen. Abizaid said, “Four to six months.”

Reflecting the division of opinion on how to proceed in Iraq, the next chairman of the committee said the administration must tell Iraq that American troops will begin withdrawing in four to six months in order to force them to take responsibility for their own future.

“We cannot save the Iraqis from themselves. The only way for Iraqi leaders to squarely face that reality is for President Bush to tell them that the United States will begin a phased redeployment of our forces within four to six months,” said Senator Levin.

Asked about his testimony in August that Iraq could fall into civil war and that the sectarian violence was as bad as he had ever seen it, Gen. Abizaid said that more recently the situation has improved, while still troubling. He visited Baghdad in recent days.

“It’s certainly not as bad as the situation appeared back in August,” Gen. Abizaid said, adding that he saw growing confidence among Iraqis in their government. “It’s still at unacceptably high levels,” he said of the sect-on-sect violence “I wouldn’t say that we have turned the corner in this regard, but it’s not nearly as bad as it was in August.”

Asked by Mr. Levin whether he was considering increasing the number of American troops in Iraq, Gen. Abizaid said he was considering “all the way from increasing U.S. combat forces all the way down to withdrawing” them. He said he would present recommendations to his superiors.

Wednesday’s hearing was the first on Iraq policy since the Nov. 7 elections, when voters handed Democrats control of Congress in part because of their frustration over the lack of progress in Iraq. Just over a third of the public approves of Bush’s handling of the war, according to AP-Ipsos polling last month. About six in 10 think the American military action in Iraq was a mistake.

It was also the first hearing since Mr. Bush announced Nov. 8 that Donald H. Rumsfeld would step down as defense secretary and that former CIA director Robert Gates would be nominated to replace him. Mr. Bush also expressed a willingness to consider fresh ideas on Iraq, although he remains opposed to setting a specific timetable for troop withdrawals.

David Satterfield, the senior State Department adviser on Iraq, told the committee that the situation must not reach the point where ordinary Iraqis believe they are better protected by unauthorized militias than by their own government.

“Hope for a united Iraqi will crumble,” if that happens, he said. “Such an outcome in Iraq is unacceptable. It would undermine U.S. national interests in Iraq and in the broader region. And it would lead to a humanitarian disaster for the Iraqi people.”

Later the committee was hearing from CIA director Gen. Michael Hayden and Lt. Gen. Michael Maples, head of the Defense Intelligence Agency.