Sentence:  Below the line spin involves setting and driving the news agenda, but also <WSD>'firebreaking</WSD>' (deliberately constructing a story to divert journalists away from an embarrassing story, e.g., Campbell's leak to the "Sunday Times" that MI6 was investigating Chris Patten when the story of Robin Cook's affair broke) or 'stoking the fire' (the precise opposite of <WSD>firebreaking</WSD> by gathering and providing information to sustain a story which an opponent is finding embarrassing, e.g. Labour spin doctors' efforts to fuel the story of rifts between John Major and the anti-Europeans in the Conservative Party) or 'undermining a personality' (e.g. the off-the-record description of Gordon Brown as 'psychologically flawed', Harriet Harman as 'incapable of joined-up thinking', while a 'senior government aide' suggested that Mo Mowlam's illness had left her 'without the intellectual rigour for her job' with another anonymous 'adviser' claiming to be 'dismayed at her erratic behaviour'. 
Meaning of the word marked with <WSD> tags:  To direct media attention at a a second story in order to minimize the impact of an embarrassing story.