((a)) ** .—** The Administrator of General Services may temporarily assign or reassign space in excess real property to a federal agency, for use as office or storage space or for a related purpose, if the Administrator determines that assignment or reassignment is more advantageous than permanent transfer. The Administrator shall determine the duration of the assignment or reassignment.

((b)) ** .—** If there is no appropriation available to the Administrator for the expense of maintaining the space, the Administrator may obtain appropriate reimbursement from the federal agency.