Alan Johnson criticised Labour's "macho politics" and failure to help more people up the income ladder as the launch of his bid for the party's deputy leadership.
The man who rose from being a postman to become the minister in charge of the Post Office as Secretary of State for Trade and Industry put "social mobility" at the heart of his personal agenda in what was seen as a coded criticism of Gordon Brown's anti-poverty strategy. Mr Johnson is considering whether to challenge Mr Brown for the Labour leadership or run for the deputy's post.
The Secretary of State for Education and Skills said: "Despite our successes, it is actually getting harder for people to escape poverty and leave the income group, professional banding or social circle of their parents. In fact, it's harder to escape the shackles of a poor upbringing in Britain than anywhere else in Europe; and about the same as in America."
He told the Social Market Foundation that "repairing the broken rungs on the ladder of opportunity" and making it easier to climb must be a top priority. "There's no point promoting 'flexibility at work' while we ignore such stubborn rigidity in our social structures," he said. "Inequality and brakes on social mobility are real problems of great concern to all modern social progressives. We must not shy away from tackling these difficulties, even though they are stubbornly engrained and throw up some tough options."
Mr Johnson also courted the support of Labour women as he attacked the infighting which erupted at the top of the party last week. "We must ensure that the self-indulgence of what was literally macho politics does not escalate into self-destruction," he said.
He faces competition for the women's vote from Harriet Harman, the Constitutional Affairs minister, who made her pitch at a TUC fringe meeting yesterday.
Although she has not formally entered the deputy leadership race, she hinted at an early decision as she accused Peter Hain, the Secretary of State for Northern Ireland, of jumping the gun by launching his bid for the post on Tuesday, even though John Prescott has not formally confirmed he will stand down when Tony Blair resigns. "By and large, I am not in favour of people announcing themselves to be candidates for jobs that are not yet vacant," she said.
Ms Harman insisted that Labour would benefit from a woman in the party's leader's role. She said: "Women in the 21st century regard themselves as equals and people expect the Government to be equal as well and expect women to have their say. A man and a woman will always work better as a team. I'm trying to counter the idea that if there is a difficult job you have to look around for the best man to do it. We now have 97 women MPs and they have made a huge contribution in all sorts of issues and they make a difference."
David Blunkett, the former home secretary, also criticised candidates for declaring for the deputy leadership before a vacancy had arisen. He told Parliamentary Monitor magazine: "I haven't enjoyed the spectacle of people throwing their hat into the ring... I won't be encouraging people until Tony Blair has decided to step down, which will inevitably lead to a period of debate and contest."
George Osborne, the shadow Chancellor, said: "Alan Johnson's withering attack shows that, under Gordon Brown, there has been a shocking decline in social mobility. The number of people in multiple deprivation has increased, and poverty has become more entrenched."