Up to 10% of SES positions can be filled as political appointments rather than by career employees.[1] About half of the SES is designated "Career Reserved", which can only be filled by career employees. The other half is designated "General", which can be filled by either career employees or political appointments as desired by the administration. Due to the 10% limitation, most General positions are still filled by career appointees.[2] It appears to be a mix of career employees and political appointments.
Whatever they area, I'm glad I'm not one. I have no such aspirations; they have to attend way too many meetings.