WASHINGTON, March 8 (Xinhua) -- The White House said Thursday that U.S. President George W. Bush would veto the legislation unveiled by Democrats that called for withdrawing American troops from Iraq by late 2008.

    Dan Bartlett, an aide to the president, said during Bush's trip to Latin America that the administration would "vehemently oppose and ultimately veto any legislation that looks like what was described today."

    "What we're seeing here is an artificial, precipitous withdrawal from Iraq based on, unfortunately, politics in Washington, not conditions on the ground in Baghdad, Iraq," Bartlett said of the legislation that Democrats unveiled Thursday.

    The House measure, which would be embedded in appropriations legislation that provided nearly 100 billion U.S. dollars the Bush administration has requested for fighting in Iraq and Afghanistan, would have U.S. combat troops out of Iraq by August 2008.

    The legislation would mark the first time the Democratic-controlled Congress has established a date certain for the end of U.S. combat in the Iraq war, which has lasted nearly four years and left nearly 3,200 U.S. troops dead, House Speaker Nancy Pelosi said at a news conference.

    The measure would "refocus our military efforts on Afghanistan and fighting the war on terrorism where it began," said Pelosi, the first woman speaker in U.S. history.

    The bill requires the Bush administration and the Iraqi government meet a series of benchmarks showing progress in bringing stability to Iraq, and that if those conditions have not been met, a 180-day withdrawal of U.S. troops would begin.

    The Democratic measure was immediately attacked by Republicans. The legislation proposed by Democrats amounted to "establishing and telegraphing to our enemy a timetable," said House Minority Leader John Boehner.

    Within hours, Senate Democrats also announced a plan to withdraw all American combat troops from Iraq by March 2008.

    "The president's strategy in Iraq is not working, and Congress must decide whether to follow his failed policies or whether to change course," said Senate Majority Leader Harry Reid.