Timeline for the last days before 'fiscal cliff'

The U.S. Capitol Christmas Tree is pictured against a backdrop of the U.S. Capitol Building in Washington, December 4, 2012 during the official lighting ceremony for the tree.

WASHINGTON (Reuters) - Midnight Monday is the deadline for the U.S. Congress and President Barack Obama to avert the "fiscal cliff" of tax hikes and across-the board budget cuts mandated under a law enacted in August 2011. With no agreement emerging from a White House meeting on Friday, congressional leaders have now roughly outlined the steps for trying to reach a deal in coming days.

SATURDAY: Staff members for Senate Majority Leader Harry Reid, a Democrat, and Republican Minority Leader Mitch McConnell will try to come up with legislation that senators of both parties might be able to support that could resolve the impasse, particularly over the question of whether existing low tax rates should be extended for everyone or just for those considered middle-class. It may take the form of Senate amendments to a bill that originated in and has already passed the House of Representatives.

SUNDAY: If they succeed, Reid and McConnell will present the bill to the full Senate for a vote and if it passes, send it to the House. Republican House Speaker John Boehner says that if it meets his requirements - if it is indeed an amended version of the earlier House bill - he will allow it on the floor for consideration and further amendment by the Republican-controlled chamber. The House has scheduled votes for 6:30 p.m. (2330 GMT).

House amendments would then have to go back to the Senate.

If all that fails, Obama and Reid will work on an alternative and submit that for a vote in the Senate.

MONDAY: If a bill has made it to the House from the Senate, the day will probably be consumed with debate and amendments and the measure might have to go back to the Senate.

Any legislation averting the cliff would theoretically need to be signed by Obama before midnight, but Congress has historically found ways to borrow a little more time in similar situations.

(Editing by Fred Barbash and Peter Cooney)