Correction Appended
WASHINGTON, May 25 — The Bush administration is developing what are described as concepts for reducing American combat forces in Iraq by as much as half next year, according to senior administration officials in the midst of the internal debate.
It is the first indication that growing political pressure is forcing the White House to turn its attention to what happens after the current troop increase runs its course.
The concepts call for a reduction in forces that could lower troop levels by the midst of the 2008 presidential election to roughly 100,000, from about 146,000, the latest available figure, which the military reported on May 1. They would also greatly scale back the mission that President Bush set for the American military when he ordered it in January to win back control of Baghdad and Anbar Province.
The mission would instead focus on the training of Iraqi troops and fighting Al Qaeda in Mesopotamia, while removing Americans from many of the counterinsurgency efforts inside Baghdad.
Still, there is no indication that Mr. Bush is preparing to call an early end to the current troop increase, and one reason officials are talking about their long-range strategy may be to blunt pressure from members of Congress, including some Republicans, who are pushing for a more rapid troop reduction.
The officials declined to be quoted for attribution because they were discussing internal deliberations that they expected to evolve over several months.
Officials say proponents of reducing the troops and scaling back their mission next year appear to include Secretary of Defense Robert M. Gates and Secretary of State Condoleezza Rice. They have been joined by generals at the Pentagon and elsewhere who have long been skeptical that the Iraqi government would use the opportunity created by the troop increase to reach genuine political accommodations.
So far, the concepts are entirely a creation of Washington and have been developed without the involvement of the top commanders in Iraq, Gen. David H. Petraeus and Lt. Gen. Raymond T. Odierno, both of whom have been enthusiastic supporters of the troop increase.
Those generals and other commanders have made it clear that they are operating on a significantly slower clock than officials in Washington, who are eager for significant withdrawals before the president leaves office in January 2009.
In an interview in Baghdad on Thursday, General Odierno, the senior United States ground commander, said any withdrawal of American troops was not advisable until December, “at a minimum.”
Even then, he said, redeployments should be carried out slowly, to avoid jeopardizing security gains.
General Odierno, who has pushed for extending the troop increase into next year, noted that units were in place or available to continue that effort through next April.
But the ideas under discussion, from the National Security Council to the Pentagon, envision reductions beginning well before then. The last time American troop levels in Iraq were anywhere near 100,000 was in January 2004, when they fell briefly to about 108,000.
One of the ideas, officials say, would be to reduce the current 20 American combat brigades to about 10, which would be completed between the spring of 2008 and the end of the year.
Several administration officials said they hoped that if such a reduction were under way in the midst of the presidential campaign, it would shift the debate from whether American forces should be pulled out by a specific deadline — the current argument consuming Washington — to what kind of long-term presence the United States should have in Iraq.
“It stems from a recognition that the current level of forces aren’t sustainable in Iraq, they aren’t sustainable in the region, and they will be increasingly unsustainable here at home,” said one administration official who has taken part in the closed-door discussions.
But other officials in Washington cautioned that any drawdown could be jeopardized by a major outbreak of new violence. Vice President Dick Cheney and others might argue that even beginning a withdrawal would embolden elements of Al Qaeda and the Shiite militias that have recently appeared to go underground.
Missing from much of the current discussion is talk about the success of democracy in Iraq, officials say, or even of the passage of reconciliation measures that Mr. Bush said in January that the troop increase would allow to take place. In interviews, many senior administration and military officials said they now doubted that those political gains, even if achieved, would significantly reduce the violence.
The officials cautioned that no firm plans have emerged from the discussions. But they said the proposals being developed envision a far smaller but long-term American presence, centering on three or four large bases around Iraq. Mr. Bush has told recent visitors to the White House that he was seeking a model similar to the American presence in South Korea.
Both Mr. Bush and Secretary Gates appeared to allude to the new ideas at separate news conferences on Thursday, though they were careful not to be specific about how or when what they are terming the post-surge phase would begin.
Mr. Gates described the administration’s goal of eventually shifting the mission in Iraq to one that is “more to train, equip, continue to go after Al Qaeda and provide support.” Such a mission, he noted, “clearly would involve fewer forces than we have now.”
Any change of course “is going to be the president’s decision,” Mr. Gates said, but one greatly influenced by assessments from General Petraeus and the new American ambassador to Iraq, Ryan C. Crocker, who are to provide an assessment of the situation in September. Mr. Gates also referred to “the possible need for some kind of residual force in Iraq for some protracted period of time.”
A rapid transfer of responsibility to Iraqi forces and withdrawal to large bases was attempted in 2005 and 2006, with disastrous results when the Iraqi units proved incapable of halting major attacks, and sectarian violence worsened.
“We’ve been here before,” General Odierno said in the interview, referring to the decisions that are coming up on how quickly to hand over authority to Iraqi units. “We’ve rushed the transition and soon lost many areas that we had before. This time it’s about having enough combat power to stay.”
But what is different now is the political environment in the United States. While Democrats in Congress relented this week and dropped demands to attach a schedule for withdrawal to a bill to finance military efforts in Iraq, White House officials concede that they have bought a few months, at best.
By the fall, they say, they are likely to lose several Republican senators and many members of the House who voted with Mr. Bush in recent weeks.
During his own news conference, Mr. Bush referred on four separate occasions to the report of the Iraq Study Group, headed by the former Secretary of State James A. Baker III and the former Congressman Lee H. Hamilton.
That report, about which Mr. Bush appeared distinctly unenthusiastic when it was issued in December, called for the withdrawal of all American combat troops by the end of March 2008. Mr. Gates was a member of the study group, though he resigned to take up his current post before the report was written.
David E. Sanger reported from Washington and David S. Cloud from Baghdad.
The White House and Pentagon officials have been discussing "concepts" to reduce the level of troops in Iraq by up to 50% and leaving a force of about 100,000 in Iraq by Mid 2008. The highest officials in the Bush administration that seem to be supporting these notions are Secretary of State Condoleezza Rice and Secretary of Defense Robert Gates.  

General David Petraeus and Lieutenant General Raymond T. Odierno have apparently not been involved with the discussions and they have both supported the current troop level increase. The current troop level surge does seem to be working but, at the same time attacks have been increased by insurgents. Also some reports have come out saying that Iran is stepping up its support of insurgents in Iraq in order to counter and maybe discredit the troop surge. Ultimately the troop level surge will be reviewed in the fall by the Congress and White House.  

''Time'' Magazine has reported from Anbar Province that the troop surge and Iraqi involvement with the help of local tribes, shieks, and their militias  have driven out a large part of Al-Qaeda and foreign insurgents out of the area.

President Bush referred to the Iraqi Study Group's Report four times in his Thursday press conference.  The Iraq Study Group was led by former Secretary of State James Baker and former Congressman Lee Hamilton.  Interestingly enough the Iraq Study Group calls for most of the U.S Army to have been withdrawn by March 2008.  

These "concepts" would not affect the current troop surge or shortly there after but, may be planned shortly after the new year. The new troop level would focus on training and supporting the Iraqi Security Forces.   

The hope of the withdrawals by the Bush Administration would be to lessen the political pressure by both Democrats and Republicans who would like to withdraw sooner rather than later from Iraq and hopefully change the political talk from short-term withdrawal to long-term influence in Iraq and in the region.