Former home secretary Charles Clarke has forecast an imminent civil war inside the Parliamentary Labour Party (PLP), insisting that Gordon Brown is a "dithering", indecisive prime minister who lacks courage and surrounds himself only with those not prepared to challenge him.
In what will be seen as a potential rallying call to Blairites left behind by the Brown administration, and to those inside the PLP who remain unconvinced that Brown can win a fourth consecutive term for Labour, Clarke says that unless Brown changes the way he governs, "it's unlikely that people will keep quiet much longer".
Clarke's statements in a newspaper interview will be dismissed as bitter comments from a cabinet minister dismissed by Tony Blair and not rehabilitated by Brown.
Along with the former health secretary Alan Milburn, Clarke tried to mount a last-minute "Stop Brown" campaign in the dying months of Blair's premiership.
But the website 2020 Vision, launched jointly by Clarke and Milburn, suffered a quick death and never lived up to its billing of being a focal point in ensuring Blairite policies remained entrenched inside Brown's Labour government.
Nevertheless the attack on Brown, with Clarke saying Brown is obsessed and "tormented" by the memory of Blair in Downing Street and that the prime minister can't make up his mind if he is "anti-Blair, rather than just post-Blair", will be rounded on by opposition leaders.
There is scathing criticism of the Brown cabinet, which Clarke dismisses as lightweight. "Gordon finds anyone challenging him really hard," says Clarke.
He also paints a vain portrait of the justice secretary, Jack Straw, who he describes as difficult to work with and "extremely status conscious". Clarke believes Straw regards himself as a prime minister in waiting should Labour find themselves needing a replacement leader sooner than expected.
Although Clarke offers advice to Brown by saying the authority of the cabinet could be boosted by the inclusion of former leading Blairites such as Milburn, the former transport secretary Stephen Byers or Patricia Hewitt, the former health secretary, he suspects it is too late for Brown to change.
"Its hard for anyone to change, especially at 56. This is the one million-dollar question. The answer is he has to change," says Clarke.
The damage from an open, public civil war will come, Clarke forecast, with a high price. He says it's unlikely Brown will still be Labour leader or prime minister in five years' time.
On the timing of his criticism, Clarke justifies it as necessary, because to do so just before the next general election, in 2010, "would be too divisive".
Last night, a senior Conservative adviser said: "Clarke is saying nothing that many Labour MPs don't know. David Cameron has said the same thing, time and time again at PMQs (prime minister's questions). The sooner a general election is called the better."
