I know some people reading this have been involved in government procurement in the past (or do it now). I have a question for you.
You're working on a procurement for a service (say meeting facilitation). Even though there are hundreds of vendors out there on the GSA schedule, you are told that only one vendor (not on the GSA schedule) is acceptable to the PM you are doing the paperwork for. When questioned, the Deputy Director for the Center backs up the PM.
Is this a sole source?