Determined to challenge President George W. Bush, US Senate Democrats are drafting legislation to limit the mission of US troops in Iraq, which would have the effect of revoking the broad war-making authority Congress granted in 2002, officials said Thursday. While these officials said the precise wording of the measure remains unsettled, one draft would restrict American troops in Iraq to combating al-Qaida, training Iraqi army and police forces, maintaining Iraq's territorial integrity and otherwise proceeding with the withdrawal of combat forces. The officials, Democratic aides and others familiar with private discussions, spoke only on condition of anonymity because rank-and-file senators had not yet been briefed on the effort. They added, though, that Senate Majority Leader Harry Reid is expected to present the proposal to fellow Democrats early next week for their consideration. The plan is to attempt to add the measure to anti-terrorism legislation that is scheduled to be on the Senate floor next week and the week after.