Scotland's charities and voluntary organisations have launched a manifesto in which they call for an increase in government funding.
More money is needed to maintain current services, charities say
They want the Scottish Executive to increase the cash they receive as part of the commitment to tackling poverty.
The call came as a number of charitable organisations closed projects because of a lack of funding.
Voluntary organisations offer a variety of services beyond those provided by the executive and local councils.
The manifesto, which was launched at The Gathering, a voluntary sector event being held in Glasgow on Monday, states that its funding should not suffer from "belt-tightening" in the public sector.
It calls on the executive to offer tax payers the opportunity to donate a proportion of their tax directly to charities.
The executive has acknowledged the value of the voluntary sector, but the 16-page document called on ministers to provide more money to allow services already on offer to be maintained.
The Scottish Council for Voluntary Organisations claimed 65% of voluntary organisations were unable to grow because of funding difficulties.
It said many organisations received three-year funding and were forced to either reduce services or close after that period.
SCVO chief executive Martin Sime said the voluntary sector could play a huge role in improving life in Scotland.
"It is through voluntary organisations that people express themselves and make commitment to their causes and make a real difference to their communities," he said.
Helen Tyrell, chief executive of Voluntary Health Scotland, added: "Politicians would ignore the strength of the voluntary sector at their peril.
"Any party that ignores the huge resource that is the voluntary sector is selling Scotland short."
Scottish Conservative leader Annabel Goldie MSP said government interference was undermining the voluntary sector.
"Volunteers and voluntary organisations play a vital role in ensuring that we all live in a strong and cohesive society.
"However, in order to carry out this role, they need to be free to come up with innovative solutions to the social problems which face our society.
"This can only be done if they are truly independent and autonomous of government."