Attorney General Michael Mukasey has agreed to postpone implementation of new FBI guidelines, after four Democratic senators raised concerns in a letter Wednesday about proposed changes that they say could permit the FBI to launch investigations of American citizens without any individualized basis for suspicion.

The letter, signed by Sens. Russ Feingold (D-WI), Ted Kennedy (D-MA), Dick Durbin (D-IL), and Sheldon Whitehouse (D-RI), concerned a draft of the Attorney General's Guidelines governing criminal and intelligence inquiries by the Federal Bureau of Investigation. The draft itself has not been made public, though The New York Times reports that the guidelines could be released next month.

The proposed rule change, first reported last week, would loosen restrictions on information sharing between agencies, and allow investigators to begin gathering information for criminal or intelligence purpose, even in the absence of any particularized evidence suggesting that a target is connected to criminal activity.

The senators fear that the new rules "might, for example, permit the FBI to conduct long-term physical surveillance of an innocent American citizen; interview such an individual's neighbors and professional colleagues, including based on a 'pretext' or misrepresentation; recruit human sources to provide information on that individual; or conduct commercial database searches on that individual—all without any basis for suspicion."