Reproduced with acknowledgements to BBC News
A leading charity figure has warned David Cameron that the pace of cuts could "kill off" the groups he needs to build his "Big Society".
Community Links co-founder David Robinson was invited to Downing St in May to discuss the social policy idea.
But in an open letter he urged the PM to "allow us to draw breath" and phase in plans to remove Legal Aid funding.
The government said charities could not be immune from cuts but it aimed to open up new funding sources.
Mr Cameron has championed the concept of the "Big Society", which encourages greater personal and family responsibility and community activism.
Community Links, an east London-based charity which provides welfare services, such as housing and debt advice, employment support and youth clubs, was praised by Mr Cameron as an "inspiring" organisation.
Mr Robinson was among charity representatives invited to Downing Street to discuss it with the PM and Deputy PM Nick Clegg after the general election.
In his letter, he said he admired the prime minister's "big hearted vision" and respected his "clear sighted perseverance" in pursuing it.
But he said he was worried about the impact of spending cuts and that organisations like his, which should be the "bedrock of the Big Society", were "wobbling".
Mr Robinson drew particular attention to changes to Legal Aid and the New Deal which, he said, put most of Community Links' budget for 2011-12 at risk.
With big changes to the welfare system due to come in, he said the government had acknowledged there would be initial confusion - and expected agencies like his to provide support.
"Removing legal aid funding for advice on welfare benefits will wipe out agencies who would otherwise resolve these problems and there is next to no chance of local councils picking up the tab when most are stopping funding, not increasing it," he said.
He said many of the disadvantaged - particularly the elderly - would instead struggle on until they reached crisis point - illness or eviction.
Warning against a "barrage of uncoordinated cuts that hit the poorest hardest" he urged the PM to phase in planned cuts and do a "serious and urgent impact assessment", giving groups more time to adjust. He proposed allowing Legal Aid to support groups giving advice until welfare reforms were "bedded down".
"Allow us to draw breath or you will kill off the agencies you need to build the society you seek," he said.
"You've staked your political future on the prospect of a stronger, more compassionate society. Don't let your own government's policies undermine it."
'Appalling financial mess'
Plans for a Big Society Bank were announced by the prime minister in July. The independent organisation would help generate income for voluntary groups and social enterprises, using funding from money reclaimed from dormant bank accounts - the aim was to have it established by April 2011.
Mr Robinson said £5bn was needed for the sector, not including the unclaimed assets, to fund preventative work with people "at risk" from social problems.
The Cabinet Office said Britain was "in an appalling financial mess" and charities and social enterprises "cannot be immune from the necessary reductions in spending".
But a spokesman said: "Despite having had to take difficult decisions, the government is determined to open up new sources of funding for charities and voluntary groups to give them independence from state hand-outs and cut away the red tape that holds them back.
"The Big Society Bank will use money from dormant bank accounts to help capitalise the sector and we have worked quickly to open up a £100m short-term fund to help charities and voluntary groups through this transition period."
He added that a total of £470m would be invested in the four years to 2014-15 to support charities and voluntary groups and money would be "targeted where it is needed most" - including a £50m Community First Fund for the most deprived areas and, £10m to match fund private donations.