The assembly includes a first arcuate tube attached to a ladder. A second arcuate tube is slidably disposed in the first arcuate tube. A lock subassembly is disposed on the first arcuate tube for limiting movement of the second arcuate tube relative to the first arcuate tube. A step lever extends along the first arcuate tube and is coupled with the lock subassembly. A first flange and a second flange each extend radially from the first arcuate tube. An actuating member defines a cam surface abutting the second flange. A bar extends through the flanges and attaches to the actuating member. The step lever attaches to the actuating member to move the actuating member and cause the cam surface to slightly deform the first arcuate tube about the second arcuate tube and engage the second arcuate tube. A foot is pivotably disposed at each end of the second arcuate tube.