Basically by being extremely cozy with reporters. Reporters who report on government happenings build contacts with people in government for leads. of course there is a quid pro quo in that the person helping them has their own motives, either on an individual (e.g. political) or government level.

If your government buddy in the State Dept. (who may himself just be a CIA agent) essentially does a lot of the "investigative work" on a major story for you by serving it on a platter, and there's an implied understanding that reporting against your buddy's narrative would end future help from the buddy, you're going to do write what he wants.