Gordon Brown faced accusations from senior Labour figures of deliberately inflaming the party's crisis as suggestions grew that a heavyweight " stop Brown" candidate would try to thwart the Chancellor's leadership ambitions.
Charles Clarke, the former home secretary, and Frank Field, the former social security minister, both claimed he had encouraged this week's manoeuvring against Tony Blair.
Mr Clarke accused the Chancellor of being a "control freak" in an interview with The Daily Telegraph, in which he hinted Mr Brown had " psychological" issues which might impact on his ability to be an effective leader.
Many Cabinet ministers were "very, very cross" at the " coup-type" activity seen in Westminster over the past week, while several former ministers were "steaming" as a result of Mr Brown's conduct, he said.
The public criticismof Mr Brown is echoed in private by some ministers. One Cabinet member told the BBC: "It would be an absolute fucking disaster if Gordon Brown was Prime Minister and I will do everything in my power to fucking stop him."
Mr Brown is the runaway front-runner to succeed Mr Blair, with strong support among union members and constituency parties, and the Chancellor's allies dismissed yesterday's critics as mavericks.
Some Blairites, however, are known to be casting around for an alternative candidate. Their preferred choices are John Reid, the Home Secretary, and Alan Johnson, the Education Secretary, although Mr Clarke also made the case yesterday for Alan Milburn, the former health secretary.
The fragile truce that settled on the party after Mr Blair and Mr Brown's public statements on Thursday was blown apart by a vitriolic attack on the Chancellor's character by Mr Clarke.
He also lashed out at Mr Brown over the pictures of him smiling. "A lot of people are very upset and cross about that. It was absolutely stupid a stupid, stupid thing to do," Mr Clarke said, in a separate interview with London's Evening Standard.
In both interviews, he warned that the Chancellor's succession to the leadership was not inevitable and said he still had to "prove his fitness" to assume the leadership.
He said Mr Brown should have "condemned from the outset" rebels who wrote to the Prime Minister demanding his resignation, whom he could have stopped at the "click of his fingers".
Questions needed to be asked about Mr Brown's failure to do so, he said. "There is a deep weakness at the core of this, which is that Gordon somehow believes that Tony might try and do him down when the only person who can do Gordon down is Gordon".
While becoming Prime Minister was not an "impossible task", Mr Brown had much work to do, Mr Clarke said. He accused the Chancellor of "eroding confidence by failing to work with his Cabinet colleagues" and said he had to "renew his relations" with senior ministers.
The onslaught was echoed by Mr Field who said he was "worried" by the Chancellor's conduct over the past week.
"He could have stopped the near-destruction of the Government if he'd wanted to but didn't, but doesn't seem to appreciate at all how near that destruction came," Mr Field told BBC Radio 4's The World at One. He suggested Mr Reid and Mr Johnson as suitable leadership candidates.
Harriet Harman, the Constitutional Affairs minister and a supporter of Mr Brown, dismissed claims that the Chancellor was responsible for the letter signed by 15 Labour MPs calling for the Prime Minister's resignation.
She hit out at Mr Clarke, adding: "We have been a very successful government, but we really do have to shut up now, otherwise we will be walking into a situation when we do the Conservatives' job for them and let them into government."
For years, Brownites have suspected the Prime Minister and his allies of attempting to find a challenger to the Chancellor. Glenda Jackson, a former minister, even told GMTV that some Blairities would rather see David Cameron than Gordon Brown in the Cabinet.
Mr Johnson has already said he will stand for the deputy leadership, but has side-stepped questions on whether he would bid for the top job. Mr Reid has yet to comment on the crisis paralysing the Government. He returns from holiday next week.
Clarke's withering assault
* On Brown smiling as he left Downing Street after meetings with Tony Blair on Wednesday: "A lot of people are very upset and cross about that. It was absolutely stupid: a stupid, stupid thing to do."
* On Brown's leadership hopes: "If you ask me if it is inevitable, I would say no. It depends on the circumstances of the election and Gordon ... setting a course for his leadership. Certainly, he hasn't done that in the past."
* On the rebels: "What he [Brown] should have done was come out strongly and distance himself from them. He could have done that with a click of his fingers. This has been complete madness."
* On Brown's personality: "Part of the problem is that he lacks confidence. He is nervous."
* On the views of MPs: "A lot of them are worried about Gordon and they need to be reassured."Reuse content