So this week, I think the government figure most under threat is ... Ahem. If only.
Losing Coulson is a significant blow for the Prime Minister. Its effects may be slow-burning, perceived as a loss of sharpness and feel for the public's gut instincts, which served the Conservative top team well as they laid into us from the opposition front bench.
But for all the continued interest in changes in personnel, changes in economics are doing more to set the political weather in Westminster.
You can feel the difference in mood since the release last week of those GDP figures that suggested the economy was at best flat when the country's hopes were pinned on rapid and sustained growth. The first major signal that the Conservatives' strategy for jobs and prosperity is not working has - marginally yet significantly - changed people's perceptions of the Government overnight.
Suddenly, the media are less inclined to give ministers the benefit of the doubt on issues that crop up. They step up their questioning as the worries of families and businesses increase.
Correspondingly, evidence that our concerns on the economy may be valid has made people more interested in what Labour has to say. New shadow chancellor Ed Balls has set the political agenda.
Serving as an opposition frontbencher now - up to four years away from a general election - probably does not feel quite the same as it would have to be part of the New Labour shadow team circa 1996.
The latest hand-wringing from a Liberal Democrat backbencher can still be of greater interest to the press gallery than the view of the official opposition.
Labour still has work to do to regain its right to be heard. But the floundering 'cut at all costs' economic strategy has ended a prolonged period of blind faith in its proponents.
John Woodcock is Labour MP for Barrow and Furness and a former spokesman for ex-prime minister Gordon Brown.