Ed Miliband has set out his vision of “One Nation Labour” as a way to create a country “where everyone can play their part”.
Taking to the Labour Party conference stage for the second time in 24 hours, Mr Miliband said he would seek to shape a country where responsibility went to the top of society and the economy worked for the benefit of all.
Mr Miliband first set out his "One Nation" idea in his keynote address yesterday, which won plaudits for its off-the-cuff style.
Answering questions from delegates in Manchester as he returned to the conference platform, Mr Miliband said: "Yesterday's speech was important not just because it was another year and a conference speech, but because it sets a very clear direction of travel for us as a party."
Setting out why his new philosophy was a break from the past, he continued: "One Nation is incredibly important to us as a country and us as a party. Old Labour is not going to answer the challenges we face because it can't stand up for the whole country.
"But nor is New Labour, because it was too silent about the responsibilities of those at the top and too timid when it comes to the vested interests of our country."
He added: "One Nation Labour offers us a chance to say that we are a country where everyone can play their part, where there is responsibility going right to the top of society, where no vested interest is too powerful to be taken on.
"And crucially it is a country where everyone can advance, an economy that works for all working people, not just a few."
Mr Miliband highlighted immigration and vocational education in his conference speech as issues where Labour needed to improve on its past record.
He said: "It is understanding who we left behind as a party as well as understanding that we need to make sure responsibility goes right the way to the top."
Mr Miliband accused the Prime Minister of having an "anyone but Cameron" approach to taking the blame for Government bungles.
The Labour leader said it was a "disgrace" that taxpayers would be landed with a £40 million bill for the failed the West Coast Main Line franchise bid.
He said: "It's very clear what needs to happen - the Prime Minister has got to get a grip. Never mind a vision, he needs to get a grip on his Government, on his useless, incompetent Government.
"He needs to tell us who knew what when, who was overseeing this bid. Which of the transport secretaries we've had under this Conservative Government was responsible for this?
"There is a pattern with this Government. Already we see them scurrying for cover. It's not our fault, they say. They always find somebody to blame - this time it's the civil servants."
Mr Miliband said the Conservatives blamed the ailing economy on snow, the Diamond Jubilee and workers holding too many employment rights, and criticised the party for rowing back on its environmental commitments.
He added: "This from a Prime Minister who said 'Vote blue to go green'. He went all the way to the Arctic to hug a husky and now he appoints any environment secretary who says he doesn't believe in climate change.
"With hypocrisy like that it is no wonder politics gets a bad name.
"But just look out next week because this is David Cameron's ABC. When you ask who is to blame for things going wrong in the country it's Anyone But Cameron. That is the reality of this Government."