The reason I say this is not because he has broken some obscure rule about when the spin doctor becomes the story he has to go, but because he is now damaging the person he is there to protect - the Prime Minister.
It has been wrongly reported that Campbell wrote my resignation letter from government and that it was he who came up with the line about when the spinner becomes the story he or she should quit. In fact, I invented that line, which seemed to be a good spin at the time - it certainly caught on. The fact is Tony Blair insisted that I be sacked for exposing Peter Mandelson's home loan. My real crime was that I worked for Gordon Brown, but what the Blair camp hated most was that I talked to journalists and they couldn't control what I was saying.
Number 10 is totally obsessed with knowing where every political story comes from. I still have a copy of a memo sent to Blair by the Number 10 press office detailing every conversation I had had with different journalists about some obscure story involving selling off the Tote. When rereading the memo this week, I thought about how much effort the Downing Street spin machine would have put into finding the MoD mole, and how they would use that information. Tragically, this ended in Dr Kelly's death. There is no doubt now that someone in the Government will have to go. Geoff Hoon is likely to be the fall guy, but the truth is that Hoon doesn't cough without asking Campbell first.
The most sickening part of this sorry saga for me was the smile on Blair's face when the BBC became the focus of the story for revealing that Dr Kelly was indeed the source for their claims that the Government had exaggerated Iraqi capabilities. And guess which papers joined the Government's attack on the BBC? All that sucking up to Rupert Murdoch certainly paid off. I actually wrote a piece for one News International title, which, I believe, was cut from the paper because it didn't attack the BBC.
Never mind that Sky News is alleged to have faked a report from Iraq, and all the BBC was doing was trying to find out the truth. While the BBC was apologising for its role in the sorry affair, Campbell was spinning away to friendly newspaper editors.
Although the Prime Minister's chief spin doctor may think he is off the hook, he has now lost all respect, not just among Labour MPs, but in the civil service, too. For years the Prime Minister has said he couldn't do without Campbell, but now, for the first time ever, his own job is on the line.
Downing Street staff joke that Blair has a sign on his desk that reads 'the buck stops somewhere else'. In this case, it has to be with Campbell.
Blair must by now realise that his comms chief is damaging him and the Labour Government. This row over the war with Iraq has been all about spin, and if Blair is ever to be believed again, the man responsible for the 'dodgy dossiers' row with the BBC just has to go.
Don't hold your breath, though. Campbell may be damaged goods, but he will not want to go under the present circumstances. Hoon can be sacrificed for now, and Campbell will go later, when the present crisis is over.
When Blair goes is, of course, a much more important question, although, if you are to believe the Westminster gossip, Sarah Brown has already been next door to measure up for the curtains. There is little doubt that Brown is odds on to take over eventually, but Blair isn't known a s 'Teflon Tony' for nothing.