Short snapped after she saw Blair's critics condemned as 'self-indulgent'

"I am one of these people who argue with people if something that I feel passionately about comes up," Clare Short once told Radio 4's Desert Island Discs. "But sometimes I think 'oh shut up Clare, leave it'."

As the full impact of her onslaught against Tony Blair sank in yesterday, it was clear that the International Development Secretary's inability to "shut up" may well have ended her political career.

Although she won the instant approval of many Labour MPs, a raft of fellow ministers rounded on her and government sources made plain that it was a matter of when, not if, she was sacked.

While her allies said that she was genuinely speaking out on a fundamental issue of principle, her critics suspected something more sinister was afoot, muttering darkly about her close links to Gordon Brown, the Chancellor.

Ever since she became MP for Birmingham Ladywood in 1983, Clare Short has rarely been without the tabloid epithet "outspoken". She resigned from the Opposition front bench twice, in 1988 over Northern Ireland and in 1991 over Labour support for the Gulf War.

Yet after her appointment to the Cabinet in 1997, she was given wide licence by Mr Blair to speak out on everything from cannabis legalisation to the curse of New Labour spin.

Her title of "conscience of the party" irked many left-wingers, given her support for the bombing of Kosovo and Afghanistan, but the Prime Minister rated her talent as a minister.

Even on Iraq, she looked for a long time as though she was happy to work within collective responsibility. However, her allies say Ms Short has spent months warning of the dangers of acting without proper UN backing. It is true that as far back as last year, she was warning she would not support "all-out war" against Iraq.

In recent weeks, as the United States' war plans moved inexorably onward, she became more agitated. In the Commons, she warned about the "nightmare" of chemical weapons being used against Iraqi civilians in a conflict. In evidence to the Commons International Development Select Committee, she attacked the US for stalling on humanitarian plans and stressed that UN authority was needed in any post-Saddam scenario.

Mr Blair was so concerned that he met Ms Short with other key ministers before the Cabinet meeting on 27 February to discuss humanitarian issues. During Cabinet, she and others stressed how essential a second UN resolution was.

She was stunned to read in the press that there was "rock solid" backing for Mr Blair, but quelled her anger. After last Thursday's Cabinet meeting, she met the Prime Minister for a "one-on-one" chat. She was particularly worried by the UK's move to impose a 17 March deadline for Iraqi compliance, fearing the Government was being "dragged along" by the Bush hawks. She wanted "another month or so". Ms Short warned US troops would be an occupying army under international law and would not have the authority to make administrative changes in Iraq.

On Friday, she cringed as she watched Jack Straw, the Foreign Secretary, at the Security Council in New York arguing for the 17 March ultimatum.

But it was only on Sunday morning, as five ministerial aides threatened to resign, that she became twitchy. Watching Patricia Hewitt, the Trade Secretary, dismiss her own PPS's concerns over war as "self indulgent", she finally snapped.

Ms Short left a message for Andrew Rawnsley, the presenter of BBC Radio 4's Westminster Hour. When he arrived for work at 3.45pm, he knew instantly he had political dynamite on his hands: she would resign without a new UN mandate.

Fearing she would lose her nerve, he got a BBC car to whisk her to the Pebble Mill studio in Birmingham and recorded the interview. Downing Street first knew of her comments only in the early evening when Mike O'Brien, the Foreign Office Minister, was interviewed for the programme.

Mr Blair was busy at Chequers phoning world leaders in a last attempt to win support at the UN. In a rich irony, the Prime Minister could not hear the programme when it was aired at 10pm as he was on the phone to the Russian President, Vladimir Putin.

After the call, Mr Blair was immediately briefed by officials. He phoned the International Development Secretary and asked for an explanation. The two spoke again yesterday morning. The call was "frosty to say the least", said one aide.

By then, the backlash was in full sway, with Alan Milburn and Peter Mandelson leading the charge. Some Blairites were convinced that Gordon Brown had some connection with the outburst.The Independent reported last year that Ms Short had told colleagues she was keen to run as Mr Brown's deputy in a leadership contest.

Acutely aware of such suspicions, the Chancellor inserted a line into his speech yesterday offering full support for Mr Blair's efforts to get a second resolution.

Dennis Turner, Ms Short's Parliamentary Private Secretary, said yesterday that his boss "wants to continue as Secretary of State."

* Tory whip John Randall has resigned because he does not consider a case has been made for war on Iraq, he announced yesterday. The MP for Uxbridge is the first opposition MP to resign on the issue.

War of words in the Labour Party

"I'm afraid that I think the whole atmosphere of the current situation is deeply reckless: reckless for the world; reckless for the undermining of the UN in this disorderly world ... reckless with our government; reckless with his own future, position and place in history." Clare Short

"I don't disrespect anyone who has a different point of view. But in the end I have to take a decision. I can't simply make a series of comments on it."

Tony Blair, Prime Minister

"The right person to speak out to, frankly, is her boss, and that is the Prime Minister."

Alan Milburn, Secretary of State for Health

"I do no think the right way is to use the airwaves at a time which is extremely sensitive, when we are trying to get a maximum consensus."

Beverley Hughes, Home Office minister

"The one person who must be smiling, if not laughing, at all of this, telling lies and defying international law again and again ... is Saddam Hussein."

Jack Cunningham, former cabinet minister

"She should talk to Tony Blair. If it is her private view then she should discuss it face to face."

Mike O'Brien, Foreign Office minister

"You are bound to ask why she should suddenly discover her principles on this matter on this particular Sunday afternoon."

Peter Mandelson, former cabinet minister