After a contentious debate in Congress on Iraq, President George W. Bush on Thursday will defend his war policy, which will leave resolution of the costly and unpopular conflict to his successor.

In a statement at the White House, Bush was expected to endorse a recommendation by his commander in Iraq, Gen. David Petraeus, to complete a limited withdrawal of combat troops by July but then impose a 45-day freeze to assess the security situation.

Bush has repeatedly said that his decisions on U.S. troops in Iraq would be based on advice from commanders on the ground, and he has opposed setting timetables for withdrawal.

He was also expected to announce that the tour of duty for U.S. troops in Iraq and Afghanistan would be reduced to one year from 15 months now served.

Bush will meet with Petraeus and Ryan Crocker, U.S. ambassador to Iraq, for breakfast at the White House in the early morning, and then make the Iraq statement at 11:30 a.m. (1530 GMT) before leaving for a long weekend at his Crawford, Texas, ranch.

Petraeus and Crocker painted a somber picture of the situation in Iraq in testimony to Congress on Tuesday and Wednesday which Democrats said gave no sign of an exit strategy after five years of war.

"Those of us who have been at this a long time obviously want the war to end as much as anybody else, perhaps maybe more," Petraeus said. "What we want to do is come home the right way without jeopardizing the gains we fought to achieve."

The Iraq war is a key issue in the presidential race, and the hearings gave three senators who want to succeed Bush in the White House - Republican John McCain and Democrats Barack Obama and Hillary Clinton - an opportunity to air their views.

NOT POSSIBLE TO END WAR BY JANUARY

White House spokeswoman Dana Perino, responding to a question about whether Bush would like to end the Iraq war before leaving office in January, said: "It's not going to be possible to do that before the end of the year, the candidates have even acknowledged it."

"We will have troops in Iraq after 2009, after he leaves office, and what the president is working to do is to make sure that he makes tough decisions now that can help make for a smooth transition when the next president takes over."

In his speech, Bush was expected to reiterate that while progress was being made in Iraq, there was more work to be done.

Petraeus and Crocker said progress under a "surge" of 20,000 extra combat troops in the last year had been mixed, with a sharp decline in violence but limited political advances needed to stabilize the country.

The United States has 160,000 troops in Iraq after boosting the force last year in a bid to reduce violence enough to allow Iraqi lawmakers to enact measures seen as critical to long-term stability.

After the pullout of 20,000 troops is finished in July, Petraeus recommends freezing force levels for 45 days to assess whether the security situation would allow for more troop reductions.

Congressional leaders met with Bush at the White House on Wednesday, and afterward House Republican Leader John Boehner was asked whether the president would endorse Petraeus' recommendations. "I think he's leaning that way," he said.

Violence has flared in recent weeks in Iraq. About 70 people have died in Baghdad's Shi'ite slum of Sadr City since Sunday in battles between militia loyal to cleric Moqtada al-Sadr and U.S. and Iraqi troops.

Tens of thousands of Iraqis and more than 4,000 U.S. troops have died since the 2003 U.S.-led invasion.