Damien Hirst's most famous work - the shark in formaldehyde - is called The Physical Impossibility of Death in the Mind of Someone Living. It could be a slogan for Gordon Brown. The Prime Minister is clinging on to the lintel of No10 by his ever more chewed fingernails. He cannot and will not admit his political mortality. There is, however, a growing number of Labour MPs who wish that he would emulate the YBA's fish skeletons in a glass case and be Here Today, Gone Tomorrow.

It is somehow appropriate that the Sotheby's auction of Hirst's work is coinciding with the disintegration of new Labour. In 1997, the bad boy of British art came to symbolise Tony Blair's Cool Britannia; now the spin-painting guru is selling at the very moment that the spin-doctored party is imploding.

Much has changed in 11 years. The Labour Party is like a photographic negative of itself in 1997. Its biggest strengths have turned into its greatest weaknesses. The discipline under which backbenchers obeyed their red-rose pagers because they thought it would help them to win has been replaced by anarchy with MPs ignoring their BlackBerrys because they fear they will lose.

The message from the centre - once imposed so effectively by No10 - is, in any case, unclear because different factions within Downing Street cannot agree what the line should be. Even the whips' office, which is meant to impose order, is in chaos because a parallel whipping operation is being run behind the back of the Chief Whip, Geoff Hoon, by the Prime Minister's trusted ally Nick Brown. In a neat twist, the formerly on-message “Blair babes” are now leading a cashmere coup.

New Labour's once legendary presentational skills have evaporated. It was Mr Brown's own spin-doctors who so hyped up the government “relaunch” over the summer that the eventual “economic rescue plan” looked like a damp squib and it was the Prime Minister's advisers who talked up a general election this time last year, damaging him for ever when it didn't happen.

After the way in which the Downing Street machine dumped on David Miliband and Alistair Darling, it is not surprising that many MPs are convinced that the recent story alleging improper behaviour by the (Blairite) Health Minister, Ivan Lewis, towards a female official was planted by No10. “They're thugs,” one minister says. And there is nothing weaker than a bully who has been challenged.

This is not just about the messengers. The emotional intelligence that helped new Labour to win power has been replaced by an inability to connect, particularly with women voters. The triangulation that allowed it to appeal to Left and Right is now seen as dithering. The hard-won reputation for economic competence - which was key to the party's victory in 1997 - is foundering as the downturn deepens.

Mr Brown's charge that David Cameron is a right-wing wolf in slick sheep's clothing is similar to the old Tory suggestion that Mr Blair had left-wing “demon eyes”. And the media will no longer give the Government the benefit of the doubt.

It is as if all the things that helped new Labour to win have turned into the faults that will make it lose. Mr Blair once compared his relationship with the voters to a marriage and when a partnership goes wrong it is the characteristics that once attracted one person to the other that become the most unappealing.

The present rebellion is not as co-ordinated as some believe. These rebels are like tribal warlords in the Afghan badlands - there are enough of them to topple Mr Brown if they gang up together, but they cannot agree on who they want to replace him as leader. Political survival is, however, focusing the minds of many backbenchers and ministers. Siobhain McDonagh and Fiona Mactaggart are seen by their colleagues as hard-working constituency MPs - their loyalty is to the party first, the leader second.

“It's serious,” says a minister who once supported Mr Brown. “Gordon can't survive another 18 months of this up to the next election. I don't think he'll stand down next week but if we have another autumn like last year he'll have to go.”

Crucially, the Cabinet is wavering. In media interviews at the weekend, John Hutton and Mr Hoon gave less-than-ringing endorsements of Mr Brown. The Business Secretary refused to criticise the rebels and agreed with them that the Government needed to set out a “stronger vision”; the Chief Whip said that he did not think a leadership contest was appropriate “at this stage”. According to insiders, their ambiguity was deliberate and preplanned.

Eight Cabinet ministers contacted by The Mail on Sunday, including Mr Miliband, Ruth Kelly, Hazel Blears and James Purnell, refused to say if the Prime Minister should lead Labour into the next election - despite being specifically instructed by No10 that they should reply “yes”. This was not just an omission - I am told that at least three consciously decided not to answer.

There is speculation that the women in the Cabinet could lead the charge, just as it is female MPs who went over the top first. “The men are wimps but the women won't be bullied,” is how one junior minister put it. And although Mr Miliband is treading a cautious line at the moment, his allies say that the Foreign Secretary has not completely ruled out resigning from the Cabinet to challenge Mr Brown.

The Prime Minister will be allowed to make his conference speech and fight the forthcoming Glenrothes by-election but if he fails to turn things around, it could get nasty after that. “There's now a consensus in the Cabinet that things can't go on as they are,” one senior source told me last night. “Gordon's got one more chance - and this time it's serious.”

The Labour Party is certainly not, as Hirst has called his auction, Beautiful Inside My Head Forever.

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