Speculation about Gordon Brown's future has increased recently
Three cabinet ministers have rallied to the prime minister's defence, insisting he is the right man for the job.
Alistair Darling, Harriet Harman and John Denham have declared their support for Gordon Brown.
Skills Secretary Mr Denham told BBC One Mr Brown had a "profound understanding of what this country needs".
Meanwhile, John McDonnell, the Labour MP who mounted an unsuccessful leadership bid last year, told the BBC that he would stand in any new contest.
Mr Denham told the BBC One's Andrew Marr programme that a summer of leadership speculation would not be helpful.
Gordon Brown is the right person for the job
Harriet Harman Deputy Labour leader
"We knew what Gordon's strengths were when people like me nominated him and supported him, and it was his profound understanding of what this country needs," he said, adding that it falls to cabinet to get that message across.
"Anything that gets in the way of all of us as a team putting that message across effectively is a distraction from what needs to be done, and is in danger of letting David Cameron win by default."
Earlier, deputy leader Harriet Harman told the News of the World that the party needed someone who had the ability to see Britain through the current economic downturn.
John Denham criticises leadership speculation
"Gordon Brown is the right person for the job," she said.
And Chancellor Alistair Darling praised the prime minister's "determination and strong purpose".
Energy Minister Malcolm Wicks also rallied to Mr Brown's defence, saying he hoped the Tories' current lead in the polls would lead to increased scrutiny of Mr Cameron's policies.
Both Mr Wicks and Mr Denham said they believed the Labour party could win the next election, even though speculation over Mr Brown's position has raged since Labour's recent by-election defeat in Glasgow East.
The ministers' comments follow an article written by Foreign Secretary David Miliband earlier this week, in which he discussed Labour's future without mentioning Mr Brown.
Mr Denham said he did not agree with some Labour backbenchers who had called for the foreign secretary to be sacked, saying Mr Miliband had made a "good case" for Labour.
The high-profile endorsements come as the BBC learned that a group of former government ministers plan to set out a series of policy ideas which they say will fill the "vacuum" left by Gordon Brown and distinguish Labour from the Conservatives.
A timetable for the policy proposals has not been decided, but they are expected to be unveiled within the next couple of months.
Meanwhile, Mr McDonnell, MP for Hayes and Harlington, called for would-be leadership challengers to "come out of the dark" and publicly declare themselves by the party's September conference.
Mr McDonnell said: "We desperately need to find a way out of this mess and to end the personal dog-fighting and to help restore some dignity to the standing of the Labour party and our government."
He later told the BBC that he would stand in a leadership contest, but called for the requirement for candidates to be nominated by 71 Labour MPs to be dropped.
Mr McDonnell's challenge of Mr Brown last year for the leadership failed when he could not secure enough signatures to get onto the ballot paper.
Shadow cabinet minister Chris Grayling said the government was "in chaos at a time when Britain faces serious challenges", and called for a general election "sooner rather than later".
"The Labour Party is clearly split right down the middle with some backing Brown and others trying to knife him," he said,
Liberal Democrat Treasury spokesman Vince Cable told the Andrew Marr Show that Labour's plummeting popularity presented an opening for his party.
"It is clear that the main political opportunities are where people are looking for an alternative to the Labour government, as they do in many northern cities and in the Midlands, where the Tories are nowhere and we are the effective opposition."
Meanwhile, the Mail on Sunday has published a secret memo in which former PM Tony Blair accused Mr Brown of playing into Tory leader Mr Cameron's hands with a "lamentable" and "vacuous" performance as prime minister.
The leaked memo, which was written in the aftermath of Labour's conference last year, says the prime minister junked Tony Blair's agenda but had nothing to put in its place.
A spokesman for Mr Blair told the paper that the former prime minister was 100% behind Mr Brown, but declined to comment on the memo itself.
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