Anti-war rebel Ms Clare Short was hanging on to her post in Mr Tony Blair's cabinet last night, though seeming delicately poised between resignation and dismissal.
At the same time Mr Blair - reeling from her unprecedented challenge to prime ministerial authority from within the government - faced a further setback as UN Secretary General Mr Kofi Annan warned that war with Iraq without the authority of the Security Council could be illegal.
The Conservatives called on Mr Blair to sack the International Development Secretary following her shock warning that she would quit the cabinet in opposition to war with Iraq without UN sanction, and her description of the prime minister's approach to the gathering international crisis as "reckless".
However the conventional wisdom at Westminster was that the Prime Minister would await the imminent Security Council vote on the all-important second resolution authorising the use of force against Iraq before determining Ms Short's fate.
The British expectation last night was that the historic UN vote is likely "later in the week" and not today, as widely expected.
As fellow ministers rounded on Ms Short - questioning the timing of her radio interview on Sunday night, and her failure to give Mr Blair advance warning of her intentions - Downing Street signalled that her position is almost certainly untenable in the longer term.
Mr Blair's official spokesman refused repeated invitations to say if Ms Short retained the prime minister's confidence and that he wished her to remain in post. Dr Jack Cunningham, Blair loyalist and former minister, said that if they failed to resolve their differences speedily Ms Short would almost certainly have to go.
At the same time, Mr Blair's failure to immediately dismiss a cabinet minister publicly questioning his judgment was regarded elsewhere as evidence of his vulnerability and acute nervousness in Downing Street that a "martyred" Ms Short could prove a powerful focal point for a growing Labour rebellion.
Martyred or otherwise, such considerations could prove academic if Mr Blair and President Bush fail to win UN backing for a war which the British Defence Secretary, Mr Geoff Hoon, yesterday signalled is but a week away. In that event, a decision by Ms Short to make good her resignation threat would propel her to the leadership of Labour's anti-war party, which is building pressure on Mr Blair for another House of Commons vote in the immediate aftermath of the UN decision and ahead of any decision to commit British troops.
Ms Short's act of defiance of Mr Blair has also increased the pressure on the Leader of the House of Commons, Mr Robin Cook, until Sunday considered the cabinet minister most likely to resign over Iraq. Downing Street sources were making no predictions about Mr Cook's likely position should war proceed without UN authority.
The pressures inside the Labour Party built further last night with Mr Annan's warning about the possible illegality of military action without UN approval.
Senior Labour MPs are likely to question Mr Blair about the advice currently available to him from his own government law officers amid continuing reports that the Attorney General, Lord Goldsmith, thinks the existing Resolution 1441 does not provide unambiguous authority for war.
In her interview with BBC radio's Westminster Hour on Sunday, Ms Short defined her confrontation with Mr Blair in terms of an absolute commitment to uphold international law.
"If there is not UN authority for military action, or if there is not UN authority for the reconstruction of the country, I will not uphold a breach of international law or this undermining of the UN, and I will resign from the government," she said.
Extending her criticism of the prime minister, she continued:
"The whole atmosphere is deeply reckless; reckless for the world, reckless for the undermining of the UN in this disorderly world, which is wider than Iraq, reckless with our own government, reckless with his [MR BLAIR'S]own future, position and place in history. I'm very surprised by it."
Despite evidence that Russian and French opposition is becoming more entrenched, Downing Street maintains that Mr Blair and President Bush are "within striking distance" of winning majority approval for the second resolution.