For weeks and months, a seemingly unruffled Prime Minister Tony Blair of Britain has weathered a gathering storm of discontent among members of his Labor Party who are incensed _ or at least unsettled _ by his lockstep alliance with President Bush.
But recently, as Blair has acknowledged that Britain might join a war in Iraq without a new authorization from the United Nations, that unease has crystallized into something more ominous.
Now, in by far the worst crisis for Blair since he took office in 1997, the dissent has given rise to a startlingly open debate about his political future.
"I don't think it is possible to exaggerate the degree of concern about the illegality of what is proposed," said Tam Dalyell, a longtime and often maverick legislator from the Labor Party. "If there is no U.N. mandate and there is not a vote in the Commons before the commitment of British troops, then we ask the prime minister to consider his position as leader of the party."
The clearest sign of the severity of Blair's predicament came late Sunday when Clare Short, an influential and often outspoken Cabinet minister, stunned the prime minister and his followers by threatening to resign if Britain joined the United States in a war in Iraq without a second U.N. Security Council resolution.
She also called Blair's stewardship in the Iraq crisis "deeply reckless."
It is a seeming token of Blair's current political weakness _ or at least of his desire to avoid the perils of Short's being cast as a martyr to peace _ that he has responded with public silence, neither castigating nor dismissing her.
Blair's destiny seems entwined with developments at the Security Council, where France and Russia have threatened to veto Britain's proposals for a new resolution authorizing the use of force in Iraq, and with the nature of any military campaign to oust Saddam Hussein.
In essence, the prime minister is fighting a two-front campaign, at both the Security Council and at home.
"If there's no second resolution and the war is anything other than short, sharp and bloodless, he'll be in serious trouble," said Charles Grant of the Center for European Reform, an independent policy organization.
The latest opinion survey suggests growing disillusion with the allies' justification for war. The survey, published in the Times of London, said 62 percent of respondents did not believe that Britain and the United States had put forward a convincing case for war, compared with 57 percent one month ago. There appears to be a growing sense in Britain that the weapons inspections are forcing Hussein to disarm, however falteringly, and should be given more time.
The survey showed that antiwar sentiment was building among Labor voters, while followers of the opposition Tories had become more supportive of a war.
Other surveys suggest that a second U.N. resolution would swing public opinion behind Blair, imbuing developments at the Security Council with potentially more political consequences for Blair than they seem to portend for the White House.
"In going to war without the sanction of the United Nations, we will see the prospects for another fine Labor government disappear," said Hilton Dawson, a rebellious legislator who was one of 122 Labor members to challenge Blair in parliament last month. "We will see the distinct possibility of this Labor Party being brought to its knees."
John McDonnell, another Labor rebel, declared, "We are asking Tony Blair to consider his position."
That same discontent has been drummed home to Blair in televised meetings in the last week with audiences as disparate as young rock fans in an MTV studio to women in a television debate Monday night.
Some of the women were mothers of people who died in the attacks on New York on Sept. 11, 2001, or in the first Persian Gulf War a decade earlier. Some harangued Blair. Many urged him not to go to war.
The misgivings have been echoed by figures as disparate as student leaders and a former Labor defense minister, Denis Healey, who said Blair's unequivocal support for Washington was "a disastrous error."
Blair stands accused of losing touch with the traditional, pacifist grass roots of the Labor Party, but draws strong backing from the opposition Conservatives.
The impact on parliamentary arithmetic is clear and not necessarily threatening to Blair. Even if more than 120 Labor legislators vote to oppose him, as last month, he can still count on the support of most of the 165 Conservatives.
In addition, Labor has a huge majority, with 411 of the total of 659 seats. But if Blair was seen to be depending on the Conservatives for his political survival while his own party revolts, his position could be weakened still further.