SYDNEY, Australia — President Bush, facing a critical juncture in the war, urged Democrats and Republicans on Saturday to unite and back the war strategy he'll lay out shortly for the next chapter of U.S. involvement in Iraq.

After days of diplomacy at an Asia-Pacific summit here, Bush is gearing up for contentious debate back home next week on Capitol Hill.

Democratic leaders want to pass legislation that would bring troops home beginning this fall, but they don't have enough votes to stop Bush from sticking to his war strategy.

Republican leaders think they can maintain the support of most GOP lawmakers, especially with recent security improvements in Anbar province and Baghdad.

In his weekly radio address, Bush recounted his surprise trip to the desert in western Iraq, where he met with Iraqi leaders and local sheiks.

Next week is a vital one for Bush and the course of the war, which will define his legacy. Gen. David Petraeus and Ryan Crocker, the U.S. ambassador to Iraq, testify to Congress about whether sending 30,000 more troops to Iraq has helped stabilize the nation.