A drilling assembly, comprising: a casing (1020); a conveyance string (1015) releasably coupled to an interior surface of the casing; a drill bit (1025) rotatable relative to the casing; a motor (1040) attached to the conveyance string and configured to rotate the drill bit relative to the casing and to carry a drilling load; a rotating seal (1055) configured to rotatably connect the drill bit to the casing; and a running tool for (1060) releasably coupling the conveyance string to the casing, the running tool having: a tubular body having a window; a gripping member radially movable between an engaged position and a disengaged position in the window; and a mandrel disposed in the tubular body and selectively movable from a first position, wherein the gripping member is in the engaged position, to a second position, to allow the gripping member to move to the disengaged position. Also a method of forming a wellbore, comprising: providing a drilling assembly comprising a casing and an axially retracting assembly having: a first tubular; a second tubular at least partially disposed in the first tubular a support member disposed in the second tubular and movable from a first axial position to a second axial position relative to the second tubular, wherein, in the first axial position, the support member maintains the second tubular axially fixed to the first tubular, and in the second axial position, allows the second tubular to move relative to the first tubular.