Labour MPs will sink or swim with Gordon Brown at the next general election despite growing criticism of his leadership, a slump in his authority and an extraordinary bout of indiscipline among some of his party’s MPs.

Whatever else may have changed over the weeks and months since Mr Brown looked as if he could lead Labour to another landslide whenever he wanted one, the party has not taken full leave of its senses, senior Cabinet ministers told The Times yesterday. There will be no challenge to his leadership, however bad the local and London elections are on May 1.

On the principle that divided parties lose elections – just ask the Conservatives – getting rid of Mr Brown now would put the Tories in power, possibly for a generation. There is also no obvious successor to Mr Brown waiting in the wings. And, anyway, it is too late. The deadline for a leadership contest this year has passed.

But anyone returning to Britain today after an extended period away might be forgiven for thinking that the Prime Minister was on his last legs.

Labour MPs have stood up to him at a meeting of the Parliamentary Labour Party (PLP), ministers have dared to question his decisions and the commentariat has been in full cry, brutally drawing attention to his shortcomings. Briefings against him have been poisonous, with some Blairite former ministers being blamed by the Brown camp for their “payback” moment. And, most important of all the polls, particularly his personal ratings, have worsened rather than improved, as at one time looked likely.

To be compared to Neville Chamberlain, as Mr Brown was at the weekend, was the cruellest barb of all. A mood of anarchy is around. Labour MPs, who once saw Mr Brown as the passport to a fourth term, are fearing the opposite.

What happened to turn Mr Brown from potential winner to potential loser so swiftly? His decline can be traced to three separate events – the aborted election, the Budget and a private meeting of Labour MPs two weeks ago yesterday.

The issues that have most damaged him have been the economy, as would be expected, and, more surprisingly, the row over MPs expenses.

Until he allowed election speculation to mount last autumn, and then ran away from it, Mr Brown had an air of invincibility among the public and his MPs. That one decision punctured it. The trail of problems that followed – Northern Rock, lost data discs, capital gains tax, nondoms – killed it for ever.

Even so, a mild recovery was under way early in the new year as Mr Brown brought Stephen Carter to No 10 as his chief strategist, and both Mr Brown and Alistair Darling looked to the Budget to consolidate it.

Although minimalist in measures and impact, it had the opposite effect. It may be remembered negatively for the ending of the freeze on alcohol duty and heavier taxes on motorists, but for voters and politicians its innate caution was a wake-up call that the economy is facing troubled times.

As charges from the Tories that Mr Brown had not used the good times to prepare for the bad times hit home, suddenly that iron reputation for economic competence – which got Labour through three elections – came under the severest questioning.

Labour strategists believe that the polls are so bad at present because they are more a referendum on the state of the economy than a reflection of voters’ choices between the parties.

Finally, the PLP. What happened at that private gathering a fortnight ago remains shocking to many who were there. It is a forum that can usually be guaranteed to provide support for the leader in difficult times. But here, suddenly, Mr Brown found himself being criticised for the decision in his last Budget a year ago to abolish the 10p starting rate of tax.

What was worse, he did not appear to understand constituents’ pain, talking instead about how he had managed to beat the Tories to cutting the basic rate, and that he had compensated the less well-off with tax credits.

With a rebellion already certain over 42-day detention, Mr Brown had another severe problem on his hands; and on top of all that there was talk of his old and new teams at No 10 falling out, and even of Cabinet ministers squaring up to each other.

The Times has been told that internal focus groups have shown that Labour is being hugely embarrassed by the row over MPs’ expenses, even though it began with disclosures about Conservative Members. Labour MPs in working-class seats tell of constituents who say to them “you are all at it” and are fed up with talk of second homes and John Lewis lists of goods that MPs can claim. That feeling, it is asserted, has led those MPs to listen more intently when their poorer constituents complain of losing out because of the 10p tax decision.

In a series of increasingly frantic telephone calls during the current Commons recess, ministers are asking themselves whether Labour and Mr Brown can get out of their present problems, or whether they will all go down together in 2010.

When Mr Brown snapped at his heels for the leadership, Tony Blair used to wonder to friends how his rival would get on without him. The nontribal members of the Cabinet have always maintained that the TB-GB partnership was greater than the sum of its parts and that Mr Brown would inevitably look diminished without Mr Blair at his side. They say now that Mr Brown should do less and not feel the need to associate himself with every news story that is happening, while showing the country that he has a strong young team around him. They feel that his BBC interview last week was disastrous in that he spent his time defending his tax changes rather than empathising with the people hit hardest by them.

Mr Brown believes that he can recover and that Labour MPs, while depressed, are not suicidal. He is gambling that his constant claim that Britain is better placed to endure world turbulence than other countries will be borne out by events and that, in a year or so, he will be able to say to voters that he helped them through the worst. Then, he believes, people will start thinking again about the choice facing them.

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