The White House Liaison is responsible for staffing their agency with the help, coordination, and approval of PPO.
Once a candidate is selected, it is the responsibility of the White House Liaison to work with agency staff (for example, at HUD, this was the Office of Executive Resources) to get the necessary paperwork so the candidate can start.
Once the candidate starts, it is the job of the White House Liaison to answer any questions about the agency, assign the appointee a desk or office space, and lay out expectations for the role.
Every position must have a position description associated with it. Once a position description is written, it must be scored by a career employee to determine the GS level. If the GS level of the candidate is higher than the position description grade, then an updated position description with more responsibilities must be written. Once the GS score of the position description is equal to the GS level of the candidate, the hiring process can proceed.