Supporters of the Chancellor, Gordon Brown, have launched an extraordinary attack on Tony Blair, portraying him as a "psychopath" and "psychotic".
Blair loyalists are furious about a string of hostile articles about the Prime Minister in the current edition of New Statesman magazine, which is owned by Geoffrey Robinson, a former Treasury minister and a close ally of Mr Brown.
The strong language was seen in the Blair camp as a "revenge attack" for a previous sideswipe at Mr Brown by a Blair aide who described the Chancellor as having "psychological flaws".
In a leading article, New Statesman makes the case for Mr Brown to take over from Mr Blair in 2005, and suggests that this date - not Labour's 1997 election victory - may prove "the radical watershed of our age".
The magazine says that "Mr Brown, like Margaret Thatcher but unlike Mr Blair, has a focus". A Brown government would constantly ask how to reduce poverty and promote equality. "Mr Blair lacks such clarity of purpose, with the result that all sorts of fancy ideas get an airing, without rhyme or reason and usually without result."
It says the Chancellor would be a bigger vote-winner than the Prime Minister because Mr Blair "has lost so much public trust over the Iraq war".
Another article in the magazine is headed "What is the point of Tony Blair?", while a third declares: "The question of Tony Blair's sanity can no longer be avoided."
It quotes Sidney Crown, a former consultant psychotherapist at the Royal London Hospital, as saying that Mr Blair "does not exist" and compares him with an actor. He adds that Alastair Campbell, Downing Street's director of communications and strategy, is "very much represented in Mr Blair's dark side, which is why they like each other ... the psychopathic personality is very quick to pick things up and shift and move about".
Dr Crown suggests that Mr Blair did not decide to lie about Iraq's weapons of mass destruction, but had been "highly selective" over intelligence material, seeing the material that appealed to him. "With all forms of psychotics, if you ask people about the consequences of what they've done they can't tell you, because they've no ability to see the future."
The former cabinet minister Clare Short, a close ally of Mr Brown, says in the magazine that Mr Blair is a "media star" who "thinks in soundbites" and "uses his charm to get what he wants".
In another article, Charlie Whelan, the Chancellor's former secretary, urges Mr Blair to sack Mr Campbell.
One Blairite minister saw the magazine's attack as part of what he called "manoeuvring" by Brownites at a time when Mr Blair faced his most difficult time since becoming Prime Minister. "They are trying to destabilise him but it won't work. The party will hate it," he said.
Another loyalist minister said: "It's a bit rich to argue that we would be a more radical government if Gordon was Prime Minister. He already controls our economic and social policy."
Sources at the magazine denied that the separate articles were designed to form a deliberate attack on Mr Blair.
Downing Street dismissed the New Statesman articles, saying Mr Blair had not gone "potty". The Prime Minister's official spokesman said the label was itself "potty".
He added: "You have got to look at what the Prime Minister has achieved in the past six months in terms of handling major international issues like Iraq, in pursuing the goal of progress in the Middle East settlement, in pursuing public service delivery at home.
"I think you will see a prime minister who has a very clear sense of direction, who understands fully the difficult issues and the difficult decisions this country is faced with, who understands the need to maintain progress and to work through the process of investment and reform."
In a separate attack on the Prime Minister, Iain Duncan Smith accused Mr Blair yesterday of telling a "downright lie" over the "dodgy dossier" on Iraq issued in February. Mr Blair told MPs this month that the Tory leader had been briefed by the chairman of the Joint Intelligence Committee on the contents of the dossier, but Mr Duncan Smith insists he did not receive a briefing until after the dossier was issued.
Mr Duncan Smith, who is seeking an apology from Mr Blair, said: "I didn't even know about its publication until the day I read about it in the newspapers. Any attempt by him to say otherwise, frankly, is a downright lie. I am very angry about having my name dragged through the mud by Mr Blair in this respect for his own purposes."Reuse content