Arnold [has] been at war with nursing groups. They want more staffs at county/city/state (government funded) hospitals while Arnold refers to them as "special interest groups" and actually said he'd "kick their butt."
By definition, they are a special interest group.
Any group that enters the political debate in order to advance their own personal agenda/benefit is a "special interest group."
I think you can't use a blanket term to cover people lobbying for tobacco companies and nurses lobbying trying to improve hospital care.
