Cabinet puts on show of support for beleaguered Blair but ministers could resign

The sight of the Cabinet throwing a protective shield around Tony Blair this weekend may prove to be the defining moment of his time in Downing Street.

Even his sternest party critics have begrudgingly conceded that the Prime Minister was a prime electoral asset. Left-wingers excluded from the New Labour "Project" found it hard to argue with the scale of the parliamentary majorities (of 179 and 167) under his leadership.

The fear within the Government is that the Iraq crisis could cause such a dramatic shift in the political landscape that it could cause Mr Blair's downfall within months.

Many of the party's activists – vital for bringing out the vote in May's elections – are in a mutinous mood. Stewards at the Glasgow spring conference excluded troublemakers from the hall while the Prime Minister spoke. But the mass display of opposition to war hours later outside the conference centre – with many Labour constituencies joining the demonstration – sent an unmistakable message.

Meanwhile, many Labour backbenchers could only be corralled into voting for fresh military action against Iraq with a fearsome whipping operation in the Commons.

But most worrying for an administration that prided itself on being able to tap into Middle England's concerns are the signs of overwhelming opposition in all sections of society to British involvement in Iraq.

The second report from the United Nations chief weapons inspector, Hans Blix, and the demonstrations in London and Glasgow – a difficult combination for the Government's case – prompted the Cabinet to stage its show of support for Mr Blair.

John Prescott, regarded by many Labour supporters as the conscience of the party, was a significant choice of advocate for his leader. His appeal for sceptics to trust Mr Blair also echoed his plea for loyalty when the late John Smith faced a rebellious party conference in 1993.

The Environment Secretary, Margaret Beckett, one of the most experienced Cabinet members, and with an impeccable left-wing background, is an important ally. And the party chairman, John Reid, is warmly regarded across much of the Labour movement for his candour and charisma.

But the fact remains that the Labour movement's political fault-lines on Iraq extend to the Cabinet. And the reality for Mr Blair is that ministers could resign if Britain joins a US-led war on Iraq without UN backing.

Robin Cook, the independent-minded Leader of the Commons, is seen by many MPs as the most likely to walk out.

Another obvious candidate for resignation is Clare Short, the Secretary of State for International Development, who in recent months has made plain her worries over the apparent momentum towards war in Iraq. But she and Mr Blair have a strong mutual respect and his emphasis on the humanitarian and moral justifications for military action will have appealed to her.

The most hawkish elements of the Cabinet are Jack Straw, the Foreign Secretary, Geoff Hoon, the Secretary of State for Defence, and David Blunkett, the Home Secretary. Sources say they have all seen intelligence material on the potential dangers of the Baghdad regime.

They also believe that a line has to be drawn in the sand now to prevent other nations gaining deadly weapons, an argument strongly advanced yesterday by Alan Milburn, the Secretary of State for Health.

Today the Cabinet stands behind Mr Blair, not least for the pragmatic reason that he is the only leader they have. But many will know that if British involvement in Iraq turns out to be a disaster, leaving Labour activists and voters in uproar, then pragmatism could also dictate that the time has come for a new leader.

Shoulder to shoulder with their leader

Margaret Beckett, Environment Secretary: "Everybody recognises the enormous political dangers to the Government and this party."

Admission of the problems Labour faces with its activists and the threat to its chances in May's council elections.

Alan Milburn, Health Secretary: "If nothing happens then Saddam remains in place, weapons of mass destruction remain there and, more importantly, it gives a green light to others."

Close Blair ally argues for a line to be drawn in the sand.

John Prescott, Deputy Prime Minister: "I trust [Tony Blair] to make the right judgements in the interests of the British people and those of the wider world community."

Appeal by minister seen as link with party faithful echoing 1993 speech in support of John Smith.

Gordon Brown, Chancellor: "We should all give Tony Blair, the leader of our party, our full support as he seeks to find an international way forward for the necessary disarmament of Saddam Hussein."

His strongest support for the Prime Minister on Iraq.

John Reid, Labour Party chairman: "It is the duty of leaders to lead, to say it as they see it, to be honest with the party and with the people, especially when they believe... this world to be in peril."

Blunt demand for loyalty from one of the most loyal Blairites.

David Blunkett, Home Secretary: "We understand how you feel because we have compassion and care."

Statement to anti-war marchers that they do not have a monopoly on compassion; part of the shift to emphasising humanitarian aims on Iraq.