2 U.S.C. § 2005

Any Member or Member-elect of the House of Representatives may file with the Architect of the Capitol a request in writing that any individual office room be assigned to him whenever it shall become vacant. If only one such request has been made for any room which shall at any time have become vacant, the room shall be assigned as requested. If two or more requests are made for the same vacant room, preference shall be given to the Representative making the request who has been longest in continuous service as a Member and Member-elect of the House of Representatives. If two or more Representatives with equal length of continuous service, or two or more Representatives-elect make request for the same room, preference shall be given to the one first preferring his request.