Former deputy prime minister John Prescott has thrown his weight behind Andy Burnham in the race to replace Ed Miliband as Labour leader.
Lord Prescott compared Mr Burnham to Tony Blair, who won three general elections for Labour, claiming the former health secretary showed many of the "skills and qualities" demonstrated by the ex-prime minister.
The high-profile endorsement of Mr Burnham will come as a further boost to the bookmakers' favourite for the leadership.
In his Sunday Mirror column Lord Prescott said: "Before Tony became our leader, he spent 11 years as an MP. In that time he learned his brief, gained the experience, handled the media and won the public's trust with an overwhelming landslide.
"I have seen a lot of those skills and qualities in Andy Burnham during his 13 years as an MP. Many people talk about aspiration but Andy is a living example - a working class lad from Liverpool who went to a comprehensive and got a place at Cambridge University."
He added: " Andy also has that one thing all leaders crave - the common touch. I've seen him in small groups and big meetings.
"People instantly warm to the guy. He's a family man who loves his football. He's not just faking it like Cameron to be popular.
"Blair wasn't the complete leader when he was elected. It took time and he made mistakes. But he had the potential, the ideas, the experience and the determination to succeed.
"Tony was a winner. We now need someone who can earn the trust of the public and has an insatiable desire to help everyone get on in life."
But Mr Burnham's bid for the leadership was condemned by health whistleblower Julie Bailey, who worked tirelessly to expose the Mid Staffordshire hospital scandal.
She told the Mail on Sunday: "While health secretary, Andy Burnham presided over a culture of denial and cover-up over NHS care scandals that cost lives in failing hospitals across the country.
"From ignoring repeated warnings about high hospital death rates, to dodging calls for a public inquiry, Andy Burnham put politics before patients every time."
She added: " We believe him to be a grossly unsuitable candidate. It would be a disaster for patients if he was ever to become health secretary again, let alone assume any higher public office."
The leadership contender's spokesman said: "Mr Burnham ordered the first and second inquiries into the terrible care failings at Mid Staffordshire, against civil service advice at the time. It is concerning that the Tories are not implementing the recommendations of those reports."
Meanwhile, Mr Burnham's rival Yvette Cooper said she will put measures to help families at the heart of her campaign to rebuild Labour after its election defeat.
The shadow home secretary said Labour had to "reach outwards" and "rebuild", winning back voters who deserted the party in favour of the Tories, Ukip and the SNP.
Ms Cooper believes she can smash the "glass ceiling" and become Labour's first permanent female leader, vowing to "shake up the system".
Mother-of-three Ms Cooper, whose husband and former shadow chancellor Ed Balls lost his Westminster seat in the general election, said Labour had to offer hope to families.
In an interview with The Sun on Sunday, she said: " We need to put families at the heart of our politics. As a mum, I feel very strongly about that because my family, my kids are the most important thing in my life.
"That has to be reflected in what we do. We have got to reach out and rebuild and that means winning back voters."
Ms Cooper has tried to present herself as a unity candidate for the party, warning against being dragged to the left or right by Mr Burnham or Liz Kendall respectively.
Setting out her pitch, she said: " We've got to show practical things we can do to help families get on, to know their kids can get an apprenticeship, have a good start in life and go to university. "
Mr Balls, who failed in his own leadership bid when he ran against Mr Miliband in 2010, has said he will not play a role in his "brilliant" wife's efforts to secure the job, insisting it's "her campaign, they are her ideas".
Ms Cooper said: "I'll always be my own person. I'll stand up for women and men across the country who want to do their own thing, have their own ideas and get on.
"Yes, that will mean challenging prejudice, sexism and different kinds of attitudes. But I think we can smash the glass ceiling and shake up the system."
Labour has been temporarily led by women before, with Harriet Harman currently acting as leader and Dame Margaret Beckett filling the role on an interim basis after John Smith's death in 1994.
But three of the four candidates in the running to replace Mr Miliband are women, with shadow international development secretary Mary Creagh also in the race with Ms Cooper and Ms Kendall.
Rushanara Ali announced her intention to run for Labour's deputy leadership, claiming the party had become "unelectable".
The Bethnal Green and Bow MP, first elected in 2010, said: "I think it's time for my generation to roll up their sleeves and get to work. I think we have an important voice within the party and outside so that we can show how we ... rebuild trust so that we can build a coalition, unite people so that we can win.
"We faced a massive defeat this time, building on the last one. We have got to be radical, we have got to take risks, we have got to be bold, not only in our ideas, which have to come from the people who rejected us as much as the people who supported us."
Ms Ali, who said supporters of her campaign include shadow education secretary Tristram Hunt and former minister Keith Vaz, told BBC Radio 5 Live's Pienaar's Politics the party had to understand where it went wrong.
Asked if Labour was too left-wing to win, she said: "I think that we weren't left-wing enough for Scotland, clearly. This is not a simple analysis you can make between the right and the left.
"We weren't capturing the middle classes and tapping into their aspirations, their hopes for their families. We lost voters on the left to the Greens, we didn't capture Liberal voters. This is a big project, there are not simple solutions."
Asked if Ed Miliband was "unelectable", she said: "I think it's a tired debate. As a party, it goes without saying, we were unelectable."
Acting leader Ms Harman insisted that the leadership contest would not be a "stitch-up by the unions" in response to questions on whether general secretaries such as Unite's Len McCluskey wield too much influence.
She told BBC1's Andrew Marr Show that under the new "one person, one vote" system "there's absolutely not going to be a stitch-up by the unions in this election."
Ms Harman added: "The ballots will not be sent out, as they have been in the past, by the unions themselves, together with a recommendation to vote for one candidate.
"It will be sent out, independently, to people who have signed as supporters of the Labour Party."
With fears that the two most experienced candidates Ms Cooper and Mr Burnham were gathering large numbers of nominations from MPs - potentially crowding out their rivals - Ms Harman added that she wanted a wide range of names on the ballot paper and a "very open contest".
Ms Harman also restated her belief that the party should not elect both a male leader and deputy leader.
"I have always said I don't think there is a place for all-male leadership teams," she said.
"We are a party of equality, we believe in women having an equal say and being at the table and a balanced leadership team is better.
"We are electing our leader and deputy leader at the same time ... with the electoral system we will have to see whether it works out like that, but I profoundly hope that we must have either the leader or the deputy being a woman."
Ms Creagh said she is "confident" of securing the required 35 nominations from Labour MPs to appear on the leadership ballot paper - naming four parliamentarians who have already declared their support.
S he also criticised Labour's proposed "mansion tax", describing it as "almost impossible to administer at a local base" and introduced without shadow cabinet consultation.
Asked if she made those arguments in the shadow cabinet to Mr Miliband and then shadow chancellor Ed Balls, Ms Creagh told Murnaghan on Sky News: "This was something presented quite late on in the election when there was no shadow cabinet.
"It was presented quite late on as the way of funding the NHS and it was presented without shadow cabinet discussion so there wasn't the chance for that to be discussed."