The White House warned on Thursday that the opposition Democrats' plan to link the Iraq war budget with a timetable for military withdrawal had "zero chance" and would face a presidential veto.

The spending and war-cutoff bill under consideration "has zero chance to be enacted into law," White House spokesman Tony Snow said. "It's bad legislation. The president is going to veto it and Congress will sustain that veto."

The Democratic-controlled Congress is holding a debate Thursday ahead of a vote Friday on the controversial 124 billion dollar measure for the wars in Iraq and Afghanistan.

President George W. Bush has urged lawmakers to approve the budget commitment in full and without restrictions on how it can be spent.

Top Democrats want to link approval of the money to a mandated withdrawal of US forces from Iraq by August 31, 2008. The party's left wing wants legislators to approve the funding only on condition that the troops begin to withdraw this year.

Snow described the bill as "fatally flawed."

"It ties the hands of our generals. It does so by putting politicians and staffers in charge of the kinds of things that need to be determined on the battlefield. That is a formula for failure," he said.