President Bush on Friday was expected to repeat his message at the Marine base in Quantico, Va., that the U.S. is winning in Iraq.

Bush was to say that continuing the fight is crucial to American security during a trip to have lunch with 250 Marines, family members and commanders at the base, just outside Washington.

Bush, firmly rejecting his opponents' calls to end the War in Iraq swiftly, ordered gradual reductions in U.S. forces in the war-torn country on Thursday night and said, "The more successful we are, the more American troops can return home."

Bush insisted that Iraq will still need military, economic and political support from Washington after his presidency ends.

Friday morning, 12 hours after Bush's address to the nation, the White House was to report that Iraqi leaders had gained almost no new ground in meeting U.S. benchmarks on bringing about reconciliation and stability. The report being sent to Congress by the White House underscored the difficulty of Bush's argument that American sacrifice was creating space for political progress by Iraqis.

The president said that 5,700 U.S. forces would be home by Christmas and that four brigades — a total of at least 21,500 troops — would return by July, along with an undetermined number of support forces. Now at its highest level of the war, the U.S. troop strength stands at 168,000.

"The principle guiding my decisions on troop levels in Iraq is: return on success," the president said, trying to summon the nation's resolve once again to help Iraq "defeat those who threaten its future and also threaten ours."

Addressing America's frustration with the protracted war, the president said, "Some say the gains we are making in Iraq come too late. They are mistaken. It is never too late to deal a blow to Al Qaeda. It is never too late to advance freedom. And it is never too late to support our troops in a fight they can win."

"Whatever political party you belong to, whatever your position on Iraq, we should be able to agree that America has a vital interest in preventing chaos and providing hope in the Middle East," the president said.

He added, "Let us come together on a policy of strength in the Middle East."

With no dramatic change in course, however, Bush's call for bipartisanship is likely to fall on deaf ears. Democrats quickly said Bush's modest approach was unacceptable, setting the stage for a fiery political debate in Congress and on the 2008 presidential campaign trail.

"An endless and unlimited military presence in Iraq is not an option," said Sen. Jack Reed of Rhode Island, a former Army Ranger, who delivered the Democratic response.

"Democrats and Republicans in Congress — and throughout the nation — cannot and must not stand idly by while our interests throughout the world are undermined and our armed forces are stretched toward the breaking point," Reed said. "We intend to exercise our constitutional duty and profoundly change our military's involvement in Iraq."

The reductions announced by Bush represented only a slight hastening of the originally scheduled end of the troop increase that Bush announced in January. When the cutbacks are complete, about 132,000 U.S. forces will be in Iraq.

Bush said Iraqi leaders "have asked for an enduring relationship with America.

"And we are ready to begin building that relationship in a way that protects our interests in the region and requires many fewer American troops."

Bush described the gradual withdrawals, and the U.S. forces still fighting in Iraq, as a compromise on which war supporters and opponents could agree.

"The way forward I have described tonight makes it possible, for the first time in years, for people who have been on opposite sides of this difficult debate to come together," Bush said.

That appeared highly unlikely, however, based on the reaction of Democratic leaders who want deadlines for withdrawals.

"The American people long ago lost faith in the president's leadership of the war in Iraq because his rhetoric has never matched the reality on the ground," said House Speaker Nancy Pelosi, D-Calif. "The choice is between a Democratic plan for responsible redeployment and the president's plan for an endless war in Iraq."

Majority Democrats in Congress are unable to muster enough votes to force an end to the war. So they are hoping to win Republican support with legislation to limit the mission of U.S. forces to training Iraq's military and police, protecting U.S. assets and fighting terrorists.

Bush acknowledged that Iraq's government has failed to meet goals for political reconciliation and security. "In my meetings with Iraqi leaders," he said, "I have made it clear that they must."

A White House report, to be released Friday, will document the failures of the Iraqi government.

The latest conclusions largely track a comparable assessment in July, the White House said. The earlier report said the Iraqi government had made satisfactory gains toward eight benchmarks, unsatisfactory marks on eight and mixed results on the rest. A senior administration official said Thursday that only one of the benchmarks — enacting and implementing legislation to allow former lower ranking members of Saddam Hussein's Baath Party to hold government positions — has moved from unsatisfactory to satisfactory.

"Iraq's national leaders are getting some things done," Bush contended. He said the Baghdad government has passed a budget and is sharing oil revenues among the provinces even though legislation has not been approved. Changes that have begun to take hold in the provinces must be followed in Baghdad, he said.

Bush's claims of security progress in Iraq were jarred Thursday by the assassination of a Sunni sheik who revolted against Al Qaeda and fought alongside Americans.

Abdul-Sattar Abu Risha, the most prominent figure in a U.S.-backed revolt of Sunni sheiks against Al Qaeda in Iraq, was killed by a bomb, dramatizing the danger faced by people who cooperate with coalition forces.

Bush had met with the sheik 10 days ago during a visit to Anbar province. Bush said that after the sheik's death, a fellow Sunni leader pledged to continue working with the United States.

Bush said Anbar, once considered lost to Al Qaeda, shows what can happen across Iraq. "They show Al Qaeda that it cannot count on popular support, even in a province its leaders once declared their home base."

Bush said he had directed Gen. David Petraeus and Ryan Crocker, the U.S. ambassador to Iraq, to report to Congress in March with their next assessment of developments in Iraq and the level of U.S. troops needed to handle security.

"Americans want our country to be safe and our troops to begin coming home from Iraq," Bush said. He said his strategy would permit "people on opposite sides of this difficult debate to come together."

Polls show Americans overwhelmingly disapprove of Bush's handling of the war, which has claimed the lives of more than 3,700 U.S. troops and cost about a half-trillion dollars. His approval rating, however, has risen slightly in the last few weeks. A FOX News Opinion Dynamics poll on Thursday showed the president's approval rating had risen to 37 percent — its highest level in five months.

In his speech, Bush directed specific messages to different audiences.

To Congress, he sought support for Petraeus' recommendations on troop levels.

To Iraqis, he said, "You must demand that your leaders make the tough choices needed to achieve reconciliation."

To Iraq's neighbors, he said efforts by Iran and Syria to undermine the government in Baghdad must end and that "the violent extremists who target Iraq are also targeting you."

To the international community, he appealed for help in revitalizing Iraq's economy and support for an expanded mission of the United Nations in Iraq.

To U.S. military personnel, intelligence officers, diplomats and civilians on the front lines, he said, "You have done everything America has asked of you."

The Associated Press contributed to this report.