WASHINGTON (CNN) -- A U.S. commander in Iraq said he believes it's not possible to withdraw troops from his region south and east of Baghdad by year's end as an influential senator called for a day earlier.
Maj. Gen. Rick Lynch said his forces would lose the edge they have gained if troops were withdrawn.
Army Maj. Gen. Rick Lynch, commander of the Multi-National Division-Center, was asked to comment on Republican Sen. John Warner's recommendation that President Bush start withdrawing U.S. troops from Iraq by Christmas.
Speaking to Pentagon reporters Friday via teleconference from Iraq, Lynch said, "Only when the Iraqi security forces come forward and say, 'OK, here I am, I'm trained and equipped, I'm ready, I'm the Iraqi army or I'm the Iraqi police,' can I turn those sanctuaries over, and that's not going to happen between now and Christmas."
Lynch, whose operations cover the central part of Iraq, south of Baghdad, said soldiers have been helped by the "surge," or additional troops, and have made strides against militants. But he said, "If we were to lose that capability, the enemy would come back." Watch Lynch discuss the effect of pulling troops »
"We would take a giant step backward," said Lynch, adding he needs the troops to fight both Shiite and Sunni militants and to confront significant Iranian influence in the region.
By next spring or summer, however, such a move might be possible if enough progress is made, he said.
Retired Army Brig. Gen. David Grange, a CNN military analyst, agreed with Lynch's assessment.
"Time is necessary for the Iraqi people to gain confidence in U.S. and Iraqi troops throughout their neighborhoods, get the commerce and other quality of life improvements to take hold, enable the weak political structure a chance to improve and exploit the counterinsurgency opportunities that success is providing from this effort," Grange said.
Warner, an influential Republican and former chairman of the Senate Armed Services Committee, on Thursday recommended that Bush announce the beginning of a U.S. withdrawal in mid-September and that those troops should be back in the United States by Christmas.
"In my humble judgment, that would get everyone's attention -- the attention that is not being paid at this time," Warner said.
He added: "I really, firmly believe the Iraqi government, under the leadership of Prime Minister [Nuri] al-Maliki, let our troops down."
Warner, a Virginia Republican who was a former Navy secretary, suggested pulling 5,000 troops off the battlefield would send "a very clear signal" without endangering the missions being carried out by the rest.
In Texas, where Bush is on vacation, National Security Council spokesman Gordon Johndroe said the White House appreciated Warner's advice but would wait for the recommendations of Gen. David Petraeus, the U.S. commander in Iraq, and the U.S. ambassador in Baghdad, Ryan Crocker, before making any decisions.
Petraeus and Crocker are to report to the White House in September on the progress of the troop surge.
Warner opposed Bush's January decision to send nearly 30,000 additional U.S. troops to Iraq. But he has so far also opposed Democratic efforts to force the president to start bringing U.S. troops home.
The surge campaign was aimed at buying time for Iraq's government to reach a political solution to the sectarian and insurgent warfare that has wracked the country since the U.S. invasion in 2003.
Warner's recommendation came on the same day as the release of the U.S. intelligence community's latest report on Iraq, which found "measurable but uneven improvements" in security in recent months. However, it concluded that Iraq's political leaders "remain unable to govern effectively."
Democrats have tried to wind down the war since taking over Congress in January, but Senate Republicans have used filibuster tactics to stymie those efforts.
After Thursday's report, Senate Majority Leader Harry Reid, D-Nevada, called on Republican senators to join Democrats to force Bush to change course -- and a senior Democratic leadership aide urged Warner to add his vote to those efforts.
"Will he [Warner] vote with us on anything? That is still the open and most important question," the aide said. "A recommendation to the president is different than voting for binding legislative language compelling the president to act."
A Senate Republican leadership aide said Friday that Warner's remarks slowed some of the momentum on Iraq that Republicans had gained after Democrats had acknowledged recent military success in Iraq.
But unless Warner were to change his vote to side with Democrats, the impact on the debate in Congress is minimal -- Republicans "aren't in any different place than they yesterday," the source said.
A Senate Democratic leadership aide had a similar opinion of the impact.
"The real question would be is Warner willing to vote to support a change of course and policy, and as of yesterday he ruled that out," the source said.
The aide suggested that Warner's recommendation was timed to coincide with the National Intelligence estimate because it gives the White House a position it might be willing to accept -- that the 5,000-troop cut might be palatable to Bush.
Warner and the Armed Services chairman, Sen. Carl Levin, D-Michigan, recently returned from a visit to Baghdad with harsh words for the al-Maliki government.
Levin said Monday that Iraq's parliament should throw al-Maliki out of office and replace his government.
Warner said he would not join that call. "But in no way do I criticize it," he added. E-mail to a friend
CNN's Jessica Yellin contributed to this report