The White Liaison is a political appointee hired under “Schedule C,” which denotes a government employee who is a temporary political appointment and whose employment ends at the end of a presidential administration.
The White House Liaison can either be placed by the White House at an agency, or the agency can put forward a candidate that the White House approves.
The hiring process is through the Office of Presidential Personnel (PPO), the White House office that oversees all political appointments.
