WASHINGTON (CNN) -- Senate Democrats will seek to replace the 2002 congressional authorization for military action in Iraq with a more narrowly defined measure that would limit the role of U.S. forces and set a goal to remove all combat troops by next March, a senior Democratic aide familiar with the proposal told CNN Friday.

The White House made it clear that it would oppose any move to rewrite the authorization, which could set off a constitutional tussle over whether, or how much, Congress can circumscribe President Bush's authority as commander in chief.

A draft resolution sponsored by Sens. Joe Biden of Delaware and Carl Levin of Michigan would repeal the 2002 authorization for the Iraq war and replace it with new language allowing U.S. forces to take on narrower, specified roles, including fighting al Qaeda terrorists, training Iraqi forces and helping Iraq defend its borders, the senior aide told CNN.

The resolution would call for combat troops that are no longer needed for these more limited operations to be removed from Iraq by March 2008, as the bipartisan Iraq Study Group recommended.

Democratic leadership sources said no decision has been made on when the resolution might be introduced, nor has a decision been made on whether to move it through the Senate as a free-standing measure or attach it to other upcoming legislation, such as a supplemental spending bill or a measure implementing the 9/11 commission recommendations.

Democratic leaders are expected to discuss how to proceed at a caucus meeting early next week, aides said.

Biden, chairman of the Senate Foreign Relations Committee and a 2008 Democratic presidential candidate, first floated the idea of revising the Iraq war authorization, which passed the Senate by a bipartisan vote of 77 to 23 in October 2002. The concept has drawn support from Levin, chairman of the Senate Armed Services Committee.

When the resolution came to a vote in 2002, Biden supported it; Levin voted no.

The senior Democratic aide said the reason for repealing the original language is that it is no longer "relevant" to present circumstances in Iraq because "the condition that prevailed when the president was given the authority to invade in 2002 no longer exists."