Jan. 10 (Bloomberg) -- President George W. Bush will add about 21,500 more U.S. troops to Iraq starting as soon as next week in what may be his final opportunity to salvage an increasingly unpopular and costly war.

In a speech to the nation tonight, Bush will present the new deployment as a move to assist Iraqis as they take greater responsibility for their security, administration officials told reporters at a briefing today. The president will tell Americans that he has won a pledge from Iraqi Prime Minister Nuri al- Maliki to beef up his military and commit $10 billion to stabilize and rebuild the country, the officials said.

Bush also will acknowledge that the U.S. erred in not moving sufficient force into Iraq earlier, an aide said. The additional 21,500 troops, at a cost of about $5.6 billion, will be used primarily to breathe new life into a strategy that its backers say never got a fair chance: Clear areas of extremists and insurgents, hold the cleared territory and rebuild.

``This may not be our last chance, but it's as near to the last chance as anything I can think of,'' Senator John McCain, an Arizona Republican who supports more troops, said in a speech at Washington's American Enterprise Institute last week.

Democrats are examining proposals to cap the number of troops or cut off funds for the troop increase. Senator Charles Schumer, a New York Democrat, said the president should lay out his strategy for Iraq before requesting additional forces.

`In Search of a Mission'

``This so-called surge seems to be a surge in search of a mission,'' Schumer said today at the Capitol. ``First we ought to see a new strategy.'' He said the Senate may vote as early as next week on a resolution dealing with the addition of more troops in Iraq, and that an overwhelming number of lawmakers from both parties would vote against the policy.

Bush met with more than 100 lawmakers in the days leading up to the speech. Democratic leaders who met with Bush today complained that he didn't ask for their input before settling on a plan and writing his speech. ``There's a difference between notification and consultation,'' House Speaker Nancy Pelosi, a California Democrat, said outside the White House. ``This was notification.''

Pelosi said the House also will vote on a resolution asking lawmakers to take a stand on whether they support Bush's policy.

Bush tonight will outline his targets for Iraq's government to meet, from reducing attacks to making headway on rebuilding water facilities, sewers and buildings. The U.S. will commit more than $1 billion toward reconstruction, the administration aides, speaking on condition of anonymity, told reporters.

Benchmarks

A key benchmark is that Iraq must establish full command of all 18 provinces by November. There are more immediate milestones, the officials said, including an Iraqi commitment to deploy one new combat brigade to Baghdad by Feb. 1 and two more by Feb. 15.

Iraqi forces will operate under new rules of engagement that will give them greater freedom to combat armed groups, including Shiite militias such as the Mahdi Army, the administration officials said. Many among Iraq's Sunni Muslim minority have complained that the Shiite-dominated government has countenanced Shiite militia attacks on Sunni civilians.

``Some members of the Iraqi Security Forces, notably the police, are contributing to sectarian violence,'' a White House fact sheet on the new strategy says.

The administration officials refused to disclose what the U.S. will do if the Iraqis fail to meet these commitments, saying that would be counterproductive to the effort and helpful to U.S. adversaries.

Still, they described Bush as increasingly impatient with Iraqi leaders' failure to live up to previous pledges and determined to hold them to their new promises. The president will make it clear tonight that the U.S. commitment to Iraq isn't indefinite, while setting no timetable, they said.

Skepticism

Skeptics doubt that more U.S. troops will make a difference almost four years into the conflict. They say that concentrating forces in one area may simply lead to more violence elsewhere -- and that the inevitable result of adding U.S. forces into the midst of such internal conflict will be more casualties.

``We'd get a lot more Americans killed and wounded,'' Representative Jim Marshall, a Georgia Democrat and a former Army Ranger who sits on the House Armed Services Committee, said earlier this week. ``We need greater security, but it should be Iraqis, the people who speak the language and drink the water and know the people, who take the lead.''

There are about 132,000 U.S. forces now in Iraq. The U.S. led the invasion of Iraq in March 2003 with about 90,000 troops. The number has fluctuated throughout the U.S. presence, rising to a high of 159,000 in January 2005 to provide greater security as Iraq selected an interim government in the country's first free elections since 1953.

`Different This Time'

Iraqi Foreign Minister Hoshyar Zebari said today there is a ``pressing'' need for more U.S. troops and the move is not too late. ``It would be different this time,'' Zebari said in a telephone interview from Baghdad. ``There is a combination of security, political and economic measures,'' and U.S. forces increases will be matched by Iraqi personnel, he said.

The central mission for the additional forces will be to help clear areas in Baghdad and Anbar province in western Iraq of insurgents and sectarian militias. They will remain in place to help provide security, giving the economic aid that is also part of the plan a chance to work.

Decisions about both the numbers and the timing of U.S. troop deployments will be tied to Iraqi performance and actions.

U.S. troops also will mount a more aggressive effort to counter activities against Syria and Iran to stem the flow of weapons into Iraq.

Deployments

As many as five combat brigades, or about 17,500 soldiers, would be sent to Baghdad to help clear the capital city of insurgents, according to administration figures. Another 4,000 troops, or two Marine regiments, will be sent to Anbar province. About 80 percent of the sectarian violence occurs within a 30- mile radius of Baghdad, the administration officials said.

The U.S. will send its first brigade as early as Jan. 15, followed by another next month, and three more in succeeding months, a White House official said. There are 15 U.S. brigades now in Iraq.

The new plan for stemming violence calls for carving Baghdad into nine districts with a U.S. battalion in each, along with three or four police stations operating around the clock. Maliki also will name a military governor for Baghdad.

White House Counselor Dan Bartlett said today Bush will acknowledge that U.S. made a mistake by not using enough force at the start of the conflict. ``The rules of engagement, the rules in which our troops would actually conduct these operations, were flawed,'' he said on CBS's ``Early Show.''

Bush will say that the U.S. commitment ``depends on Iraq taking specific steps to curb sectarian violence and make other moves to deal with political and economic problems and that ``benchmarks have to be met,'' Bartlett said.

To contact the reporters on this story: Roger Runningen in Washington at rrunningen@bloomberg.net; Ken Fireman in Washington at kfireman1@bloomberg.net

Last Updated: January 10, 2007 16:49 EST