David Cameron has fought back against accusations that his vision of the Big Society is simply a "cover" for Government spending cuts.
Writing in The Observer, the Prime Minister said that his initiative to hand power to local communities and voluntary organisations was intended to change the way Britain was run.
He acknowledged however that at a time of spending restraint, it would benefit society if people were prepared to volunteer more.
"Building a stronger, bigger society is something we should try and do whether spending is going up or down," he said.
"But there is a broader point to be made. As the state spends less and does less - which would be happening whichever party was in government - there would be a positive benefit if some parts of society were to step forward and do more."
His intervention came after Dame Elisabeth Hoodless - who is standing down as executive director of Community Service Volunteers, Britain's biggest volunteering charity - warned that spending cuts could obliterate the existing volunteer base.
Mr Cameron insisted that ministers were opening up billions of pounds worth government contracts so that charities and social enterprises can compete for the first time.
"The scale of this opportunity dwarfs anything they've ever had before," he said.
He acknowledged however that "while the opportunity lies in the future", local councils were seeing their budgets cut now.
In order to bridge the gap, he said that ministers would be launching a transition fund to help charities bid for bid those contracts and a Big Society bank to provide some working capital for the successful applicants.
"We are not naively hoping the seeds will grow everywhere of their own accord; we are helping to nurture them," he said.
"That's why we will soon be announcing the partners who will help us deliver our commitment to provide 5,000 community organisers in the areas where they are needed most."
Mr Cameron also dismissed suggestions that the Big Society was too vague a concept to mean anything.
"True, it doesn't follow some grand plan or central design. But that's because the whole approach of building a bigger, stronger, more active society involves something of a revolt against the top down, statist approach of recent years," he said.
"The Big Society is about changing the way our country is run. That's why the Big Society is here to stay."
Labour leader Ed Miliband said that the Big Society was a "failure" which had been undermined by the Government's cuts.
"No one can volunteer at a library or a Sure Start centre if it's being closed down," he said in an article for The Independent on Sunday.
"And nor can this Conservative-led government build a Big Society while simultaneously undermining its foundations with billions of pounds worth of cuts to the voluntary sector."
He added: "What does all this substance and style remind us of? The early 1980s, and the Thatcher government which appeared intent on ripping apart our social and economic fabric."
The Archbishop of York John Sentamu said investment was needed to allow the Big Society to flourish.
Asked on BBC1's Andrew Marr Show about the effect of cuts on charities, he said: "I think everybody has got to be concerned, I don't think that Kenneth Clarke was just speaking out of turn that once these cuts begin to come they will be very deep and they will cause quite a lot of difficulty."
He added: "The Big Society, which is right, has got to build capacity and investment has got to go into it."