Gordon Brown’s allies rounded on David Miliband last night, accusing him of egotism, misjudgment and of damaging the party by setting out his vision for Labour’s future.

MPs close to the Prime Minister denounced as self-serving a newspaper article in which Mr Miliband laid out, without a single mention of Mr Brown, how Labour could beat the Conservatives.

In urging MPs to find the confidence to make Labour’s “case afresh”, Mr Miliband was widely interpreted as preparing the ground for a leadership bid. At the very least, his intervention has ensured that Mr Brown will remain dogged by speculation over his future throughout the summer and into the autumn.

A Labour MP close to Mr Brown accused the Foreign Secretary of handing the Tories a priceless political advantage. “David had the opportunity to close this story down today. I am appalled that his judgment has been so clouded by ego that he has failed to do so. He says his intention is to turn Labour’s fire on David Cameron, but it has had precisely the opposite effect.”

The pressure on Mr Brown increased this morning when Ivan Lewis, the Health Minister, directly criticised his leadership. Mr Lewis said that the Prime Minister should stop being timid, adding that he needed to show “bold and decisive leadership”.

A Downing Street source insisted on Tuesday night that Mr Brown was relaxed about the Foreign Secretary’s article. Mr Miliband’s aides refused to say whether he had sought approval for its contents with No 10. It is thought that Mr Brown was sent the finished version only after it had been submitted.

Yesterday Mr Miliband refused to rule out mounting a challenge and repeated his offer of a “clear vision” and “significant change” for Labour.

His protestations of loyalty to Mr Brown were notably half-hearted when he faced questions at a Foreign and Commonwealth Office press conference, originally convened over the Balkans. He refused to say how long he expected the Prime Minister to remain in the job and emphasised the importance of the Cabinet. “Gordon will lead us forward, with the rest of us having a contribution to make,” he said.

Asked why he had failed to mention Mr Brown in his article, he said: “The debate has to be about issue and argument, not personality.” He added: “There is a very clear Labour vision for the future which offers change, significant change. And there is an emptiness about the Conservative Party that means we can get at them in a very serious way, and that is the right approach for the party.”

Mr Miliband avoided saying that Mr Brown would lead the party into the next election. “His leadership has shown itself to be of strong value, and one which shows itself to have brought a team around it who are able to make a contribution. Do I think Gordon can lead us into the next election and win? Yes, I’m absolutely sure of this,” he said.

His friends countered claims that he had been self-serving. “How can it be self-serving to seek to address Labour’s problems?” one demanded. “We had a terrible result in Glasgow East and a lot of people in Labour are in shock.”

The resolution of Mr Miliband, a Blairite, not to retreat from his call for change, was strengthened by strong private support for his stance from MPs and ministers, according to allies. Mr Brown’s supporters remain convinced, however, that the Foreign Secretary will pull back from the brink of a full-frontal assault this autumn. They believe that his intervention was “finely calibrated” to prevent him being overhauled as Mr Brown’s most likely successor.

Other contenders, such as James Purnell, the Welfare Secretary, and Andy Burnham, the Culture Secretary, have emerged in recent months. Mr Miliband is said to have been worried that the disaffected group of Blairites who will form the core of any rebellion against Mr Brown would transfer their loyalty to another candidate unless he made a clear signal of intent.

Mr Miliband is said to have been deeply affected by his failure to stand against Mr Brown last summer. A desire to escape the fatal “ditherer” tag is likely also to have played its part.

The Foreign Secretary’s decision to rally Labour was taken after a below-par speech by Mr Brown last Friday, the day after the by-election defeat in Glasgow East. “At least two Cabinet ministers have said to me that that was when he lost it,” a senior party figure said yesterday of Mr Brown’s performance at the national policy forum, at the University of Warwick. Another is said to have been particularly bemused when the Prime Minister diverted from his familiar roll call of global challenges to deliver a rambling passage on electric cars.

Mr Miliband made a point of drinking pints of bitter with union leaders and activists, while sharing their dismay, long after Mr Brown left for his holiday in Suffolk.

For the remainder of the weekend and into this week Mr Miliband calculated his options, calling his network of informal advisers, friends and colleagues. He decided that, at the very least, he could not go off for his own two-week holiday in Minorca without leaving a marker.

The Foreign Secretary was advised last summer that he lacked the support, both among MPs and activists, to take on Mr Brown. While the Prime Minister’s support has crumbled, well-placed observers advise against an assumption that loyalties have transferred to the Foreign Secretary. The rump of Blairite former ministers irreconcilable to Mr Brown, which includes Stephen Byers, Charles Clarke, Hilary Armstrong, George Howarth, Janet Anderson and others, is far too small, and too divisive, to deliver a knockout blow to the Prime Minister.

With Mr Brown showing no signs of going quietly, and Mr Miliband determined to stand his ground, it is difficult to disagree with the MP who yesterday predicted that Labour was facing “a very bloody civil war”.

In his own words . . .

“There’s a very clear Labour vision for the future which offers change, significant change”

“Let’s stop feeling sorry for ourselves, enjoy a break and then find the confidence to make our case afresh”

“Gordon Brown is the leader of the Labour Party and he will lead us forward”

“The Labour Party never does mad things. We’ve got to be a responsible party of government”

“Gordon’s leadership, I think, is one that has shown itself to be of strong values”

“Do I think Gordon can lead us into the next election and win? Yes, I’m absolutely sure of this”

“I’m not campaigning for anything other than a successful Labour government”

“The odds are against us, no question”

Make-or-break time for Brown

September

Cabinet reshuffle? If Gordon Brown is to make changes to his top team, he will probably do so in the first week or two of September, before Labour’s annual conference

Economic recovery package? Mr Brown must attempt to address key voter concerns of economic uncertainty, falling house prices and rising food and fuel costs with a credible economic recovery plan

TUC conference: September 8-11 The Prime Minister will address the Trades Union Congress in Brighton, a key audience within the Labour movement

Labour conference: September 20-24 Over five days in Manchester, Mr Brown will seek to regain the momentum – and support of his party – while delivering one of the most important speeches of his political life

October

Parliament returns: October 6 The mood of ministers in the first days could set the tone for Mr Brown

Embryology Bill Final votes in the Commons on embryo research and backbench amendments to liberalise abortion law

42 days’ detention Peersare expected to reject a Commons vote to allow terror suspects to be held for 42 days without charge, followed by a tight vote by MPs on whether to overrule them

November-December

PreBudget Report A critical moment to reveal measures to help cash-strapped families. May scrap higher rates of car tax and rewrite fiscal rules to increase borrowing

Queen’s Speech Programme of legislation for the next parliamentary session, setting the tone for the year

Times Recommends

• How I lost the gift of joy for a while
• Why Ann Widdecombe has got it wrong
• Alas, it’s the end of the road for petrolheads