By Ian Dunt
The full range of Tony Blair's negative emotions towards Gordon Brown has finally been laid out in new extracts from Peter Mandelson's autobiography.
The former business secretary said Mr Blair had told him Mr Brown was "mad, bad, dangerous and beyond hope of redemption".
He also described him as "flawed, lacking perspective and having a paranoia about him".
The Blair-Brown rivalry became one of the defining characteristics of British politics during the New Labour period.
The two men were close friends in opposition and together helped create the New Labour project. But Mr Brown never got over Mr Blair's successful leadership bid following the death of John Smith.
The deal reached at the time - that Mr Blair would then step down and make way for Mr Brown - was reneged upon before the prime minister was forced to step down in 2007.
Lord Mandelson, whose memoirs are being serialised in the Times, said Mr Blair broke his promise, made under duress, not to fight the 2005 general election.
The fellow New Labour architect also admitted being part of a plot to break the Treasury in two - a plan branded Operation Teddy Bear - to rupture Mr Brown's power base.
Another effort to neutralise Mr Brown saw Mr Blair toy with the idea of sending him to the Foreign Office, but he became concerned that Mr Brown might resign and become a potent threat on the backbenches.
Mr Brown became so problematic that even John Prescott, who, as deputy prime minister, often brought the two men together to make peace, became afraid of the chancellor.
"He knows there's something wrong with him," Mr Blair said.
Mr Brown eventually demanded an exit date when Mr Blair went back on his promise and decided to lead in the 2005 election.
Mr Blair said: "He's like something out of the mafiosi. He's aggressive, brutal... there is no-one to match Gordon for someone who articulates high principles while practising the lowest skulduggery."
The drip feed of extracts from Lord Mandelson's book, while not particularly revealing or informative, has served to dredge up the uglier aspects of the party's past.
Lord Mandelson is understood to have wanted the book to emerge now, when any future election is still a long way off, but the serialisation in the Times has served to toughen the job of those running for Labour leader.
Speaking to LabourList, Any Burnham, shadow health secretary, tried to distance himself from the stories.
"Labour needs to make a clean break from the self-indulgence, the arrogance, the elitism, the factionalism that represented the worst of the New Labour years," he said.