What is the definition of "political staffer" here? Is that someone who is hired as an assistant by an elected politician (i.e. a spin doctor)? And in general

What is the definition of "political staffer" here? Is that someone who is hired as an assistant by an elected politician (i.e. a spin doctor)? And in general is booted out if the someone new gets elected in. Or is it a civil servant who would stay on regardless if the politician change? In the former case, it is understadable that you would want someone under you who shares your politics. In the latter case obviously it shouldn't take place.