Original sentence: Some defenders of Dan Rather and CBS, including a member of Congress, have alleged that Republicans, possibly Karl Rove and / or Roger Stone, preempted the controversy over President Bush's service record in the Texas Air National Guard by supplying the false Killian documents used in the 60 Minutes report in order to discredit a potentially legitimate source of criticism
Edited sentence: Some defenders of Dan Rather and CBS, including a member of Congress, have alleged that Republicans, possibly Karl Rove and / or Roger Stone, preempted the controversy over President Bush's service record in the Texas Air National Guard by supplying the false Killian documents used in the 60 Minutes report in order to discredit a potentially legitimate source of criticism (see dirty tricks)