A mounting system for an architectural covering including a pair of mounting brackets, a roller operably connected to each of the mounting brackets, and an end plug at least partially received within the roller and operably connected to one of the mounting brackets. The end plug selectively transitions between an extended position and a retracted position and includes a sleeve, a plunger received within the sleeve, and a spring at least partially received within the plunger for biasing the plunger away from the sleeve. The plunger includes a center or body section and at least two radially spaced tongues extending from a first end of the center section. In the extended position a first portion of the plunger projects from the sleeve and in the retracted position at least a portion of the first portion of the plunger is received within the sleeve.