Where is all of this information coming from? Some of it may indeed be the fruit of dogged legwork by intrepid investigative journalists. Some of it may come from disgruntled people from each candidate's past. Giuliani, for example, has made many enemies on both sides of the law. But a good deal of material comes from opposition researchers. Reporters may deny it, but in a 2004 Atlantic Monthly article (subscription required), Joshua Green wrote of oppo:
Implicit in this process is the news media's cooperation in carrying out the work of campaign operatives—usually without disclosing that fact to readers and viewers. If gathering opposition research is a science, disseminating it is very much an art. "Usually you can find stories that match up with the dynamics of different media outlets," [Democratic operative Chris] Lehane explains. "If you have videotape, you take it to a television outlet. If it's a complicated financial story, you take it to The Wall Street Journal. Something on special interests you take to The New York Times. It's all part of the process."
Offensives can be executed in two ways. The first is through the more or less straightforward leaking of information that will prompt a negative story. Jason Stanford says, "It's easy to move stuff into the news media, because conflict is always a better story." Strategists know which reporters are the easiest marks when it comes to placing stories. The second is the more complicated ricochet attack. "You try to give an item to the press," the Republican consultant John Brabender recently told me, "and if they write a story, there's the basis for your ad. You're trying to create a headline you can use in your ad."