Democratic lawmakers in the U.S. Senate are drafting legislation that would effectively withdraw the 2003 authorization Congress gave for the invasion of Iraq. The precise wording of the measure remains undecided, but the legislation would seek to narrowly define the mission of U.S. troops still in Iraq and push towards a withdrawal. One version of the legislation would restrict American troops in Iraq to fighting Al Qaeda, training Iraqi army and police forces and protecting Iraq s borders as combat forces prepare to withdraw. Majority Leader Harry Reid (Democrat from Nevada) is set to present the proposal to next week, and is expected to try to add the measure to anti-terrorism legislation scheduled to be debated later this month. But any legislation that attempts to limit President George W. Bush s commander in chief powers is likely to meet with fierce opposition from Republicans, and could face a presidential veto. The Senate plan also differs from the approach being taken by House of Representatives Democrats, who pushed through a non-binding measure criticizing an increase in U.S. troops in Iraq last week. House Speaker Nancy Pelosi and leading war critic Representative John Murtha (Democrat from Pennsylvania) are championing legislation that would require the Pentagon to adhere to strict training and readiness standards in the case of troops ticketed for the war zone. But some Senate Democrats warn that measure would have little chance of passing and could allow Republicans to claim that Democratic lawmakers denied reinforcements to troops already in the war zone. Several Senate Democrats have called in recent days for revoking the original authorization that Bush sought and won from Congress in the months before the U.S.-led invasion that toppled Saddam Hussein. That measure authorized the president to use the armed forces as he determines to be necessary and appropriate ... to defend the national security of the United States against the continuing threat posed by Iraq.