"I believe strongly that politicians in Washington shouldn't be telling generals how to do their job," he said.
"I believe artificial timetables of withdrawal would be a mistake."
"The chances of success [in Iraq] are essentially zero because the Iraqi people have no voice"
Non Sequitur, Cadiz, Spain
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Meanwhile, the violence continued in Iraq on Monday, with nine US soldiers killed in Diyala province, northeast of Baghdad, when an explosive-rigged vehicle was detonated near a patrol base.
Twenty soldiers and one Iraqi civilian were wounded.
Also on Monday, at least 46 people were killed and more than 100 wounded by suicide bombers in separate attacks in at least five locations in Iraq.
One attack hit a Baghdad restaurant near the heavily fortified Green Zone that killed three, police said.
David Obey, the house appropriations committee chairman, has acknowledged that the Democrats do not have the votes to overcome Bush's veto.
But he felt the move would let the Iraqis know that the US military commitment was not open-ended and further press Bush to look for a way "to extricate ourselves from this civil war".
Jerry Lewis, Obey's Republican counterpart on the committee, said the legislation meant "congress is preparing to send a message of surrender" to its enemies in Iraq.
Harry Reid, the senate majority leader who last week said the war in Iraq was "lost", accused Bush on Monday of being out of touch.
"The White House transcript says the president made those remarks in the state of Michigan. I believe he made them in the state of denial," he said, referring to Bush's previous remarks asserting progress in Iraq.
"It has now been three months and despite the president's happy talk, no progress has been made," added Reid.
Bush has summoned General David Petraeus, the US commander in Iraq, to Washington in an attempt to build congressional support for continuing the war.