Bennett, who signed for Leeds United 12 months ago from Birmingham has found opportunities at Elland Road difficult to find, and in the past has been a target for the Blades on several occasions.
The move to bring a new goalkeeper comes after the Blades secured promotion to the Premiership whilst Leeds dropped at the final hurdle with a 3-0 loss to Watford in the Championship Play-Off final. The move is also triggered by Phil Barnes joining Grimsby Town yesterday.
Walker - who was named a target the other day by Blades-Mad has featured very little last season; this owing to the injury he sustained in their Play-Off final win over Preston North End (1-0) in 2005.
Belgian keeper Nico Vaesen who is also targeted by keeperless Sheffield Wednesday has also been seen as a move by Neil Warnock, he played just seven games for the Blues last season.