House of Commons, 4:56pm: The moment Tony Blair lost his authority

Mr Blair's first Commons defeat since coming to power in 1997 was heavier than expected and provoked speculation at Westminster about how long he could remain Prime Minister. Some allies admitted privately his tenure could be shortened if Labour backbenchers inflict further defeats in the next few months over his planned reforms on education, health and incapacity benefit.

After staking his authority on the police's request for greater detention powers - which came after the London bombings in July - Mr Blair sat grim-faced and shaking his head in the Commons as it was announced that the 90-day detention plan had been rejected by 322 votes to 291. A total of 49 Labour backbenchers joined the Tories and Liberal Democrats to reject the proposal.

The MPs then added to Mr Blair's embarrassment by voting in favour of a 28-day detention limit - up from the present 14 days but well short of the 60-day fallback position favoured by the Government.

In a round of television interviews last night, an unrepentant Mr Blair denied the setback would force him to stand down earlier than planned. However, some cabinet ministers believe the blow to his authority will increase the pressure on him to name a date for his handover of power to Gordon Brown, the overwhelming favourite to succeed him.

Mr Brown's allies are growing frustrated at the damage they believe is being done to Mr Brown's inheritance by Mr Blair's reluctance to name the day. Senior ministers may now swing behind Mr Brown in pressing Mr Blair to outline his departure timetable for the sake of party unity. "He has got to name a date," said one Brownite MP.

Mr Blair hinted at a possible timetable when he addressed Labour MPs on Monday, saying he needed 18 months to see through his package of reforms. That could mean stepping down in the spring of 2007, perhaps on his 10th anniversary as Prime Minister in May.

However, some Labour MPs predicted he might be forced out next year unless he watered down "Thatcherite" policies to inject more market forces into public services.

Mr Blair acknowledged the defeat would be interpreted as a clear sign that his authority had been gravely weakened. "People will say that. That is not the issue for me. The issue is doing the right thing to protect this country," he said. "I have no doubt where the country is on this. The country will think Parliament has behaved in a deeply irresponsible way today."

He insisted terrorism laws were "completely different" to the domestic reforms that were the Government's central programme.

Downing Street claimed the vote on the 90-day limit was not an issue of confidence because the plan was originally proposed by the police rather than the Government. Although Mr Blair's official spokesman said the Government accepted the MPs' decision on a 28-day limit, he said the question of a longer limit was bound to return in future because of the new terrorist threat facing the country.

Mr Blair will try to send a "business as usual" message when he chairs the Cabinet's weekly meeting today. Some ministers believe he may seek to restore his authority by carrying out a wider than necessary cabinet reshuffle when he fills the vacancy left by the resignation of his ally David Blunkett last week.

Bookmakers cut their odds on the Prime Minister quitting next year and Michael Howard, the Tory leader, called on to him to consider going now. Mr Howard said: "Mr Blair's authority has been diminished almost to vanishing point. This vote shows he is no longer able to carry his own party with him. He must now consider his position."

During angry exchanges at Prime Minister's Questions, Mr Blair prepared the ground for a defeat by saying: "Sometimes it is better to lose and do the right thing than to win and do the wrong thing." He rounded on a Tory gibe that he was in danger of creating a police state. "We are not living in a police state, but we are living in a country that faces a real and serious threat of terrorism," he said. "Terrorism that wants to destroy our way of life."

There was a clear sign that the Bill was in deep trouble when Gordon Brown was called back for the vote from Israel as soon as he landed in Tel Aviv and Jack Straw, the Foreign Secretary, interrupted a visit to Moscow.

On a day of high tension, Labour whips warned repeatedly that the Government was "30 votes short" on the 90-day proposal. But some potential rebels saw that as arm-twisting, and a Home Office source admitted after the result: "It's really bad. We were expecting it to be much closer than it was."

John Reid, the Defence Secretary, said the Government had been rocked. "It's a loss for the police, it's a loss for the country, it's a loss for counter-terrorism, it's a loss for the Government, it's a loss for all of us," he said. Another minister said: "There is a core of serial offenders who are doing all they can to undermine the Prime Minister. They can have an impact when our majority is 66."

Pat McFadden, a former Blair aide, insisted: "This is not about the Prime Minister's share price. This is a judgement on how we combat terrorism."

But Frank Dobson, the former health secretary, who voted against the Government, said: "After the general election, Tony Blair said he would listen. He now needs to start listening as the opposition on his plans for health and education is much bigger than on this."

Another rebel, Clare Short, the former international development secretary, said: "Forty-nine Labour MPs had enough backbone to stand up for what was right."

Paul Flynn, Labour MP for Newport West, said: "The Government is going to face a winter of discontent."

90-DAY DETENTION

For: 291

Against: 322

The other battlefields

HEALTH - the Health Secretary, Patricia Hewitt, will publish a White Paper in December on NHS reform, to increase patient choice in those parts of the NHS used most often, such as GP surgeries and home visits. Labour MPs fear that thousands of the NHS's non-hospital staff could become employed by outside organisations, including private firms.

SCHOOLS - the Education Secretary, Ruth Kelly, published a White Paper two weeks ago to increase parental choice, giving schools more power to govern themselves and changing admission procedures. The Deputy Prime Minister, John Prescott, has already objected that the proposals undermine local education authorities.

WELFARE - David Blunkett was due to publish a White Paper last month on reducing the cost of disability benefits by helping claimants return to work. Critics fear that it will cause real hardship. Mr Blunkett's successor as Work and Pensions Secretary, John Hutton, is also committed to welfare reform, but he may not have sufficient authority to push it through the Commons.

DAVID WINNICK, LABOUR

VOTED AGAINST 90-DAY DETENTION

"I reject that the carrying of my amendment is in any way aimed at the Government or the Prime Minister. Monday's parliamentary party meeting showed that he has support from the majority of Labour MPs."

PETER KILFOYLE, LABOUR

VOTED AGAINST

"The storm clouds are gathering over Tony Blair. He has lost much of the party. For him to bounce back now would require such fundamental changes to his approach that it's impossible for me to predict it."

ANN CRYER, LABOUR

VOTED AGAINST

"I don't think this harms the future of the PM. My guess is he will lick his wounds and bounce back. But I could be wrong. I think he has made up his mind on when to go, but maybe he will feel so fed up he decides to go."

GEOFFREY ROBINSON, LABOUR

ABSTAINED

"It will make Tony Blair a bit more careful now. It was a serious warning shot. He will have to take Parliament more seriously and take the Parliamentary Labour Party more seriously."

IAN GIBSON, LABOUR

VOTED AGAINST

"Blair looked shaken, but I have this feeling he will just rise again and carry on as before. He will be prepared to see how backbenchers behave on the issues coming up such as health, education and benefit."

MARK FISHER, LABOUR

AGAINST

"Blair's future depends on how he reacts to this. There is no reason why he shouldn't go at a time of his own choosing. But if he ignores this, then calls for him to go sooner rather than later will crescendo."

PAUL FLYNN

AGAINST

"This vote has left him wounded and he can only get health and education legislation through with Tory votes. Now would be a good time to set out the road map to his departure from Downing Street."

MICHAEL HOWARD, CONSERVATIVE

AGAINST

"Parliament did its job of testing arguments put forward by the Prime Minister and found them to be inadequate and poorly argued. This devastating defeat is a searing indictment on his judgement."

CHARLES KENNEDY, LIBERAL DEMOCRATS

AGAINST

"This is a good day for parliamentary democracy. It was the Prime Minister who chose to make this issue into one of confidence and it's a bad day for his authority. This is now a chastened prime minister."

PAUL FARRELLY, LABOUR

FOR

"The signal this evening's vote gives on health and education is that we are facing meltdown in the way the Government is trying to force through divisive policies. I hope they take note."

PAT MCFADDEN, LABOUR

FOR

"This is not about the Prime Minister's share price. This is a judgement on how we combat terrorism."

DR IAN PAISLEY, DUP

AGAINST

"Blair's authority has gone. He should have a 60-odd majority, he has lost that. He has not done well. In no way could you put any sugar on that cake. Indeed it isn't even a cake. It is a crust."