The campaign reflects growing concern that statutory grants for voluntary organisations will all soon be replaced by public service contracts.
The coalition, which includes the umbrella body for local voluntary sector infrastructure bodies Navca, the Directory of Social Change, the Women's Resource Centre and the Community Foundation Network, argues that grants enable greater innovation than contracts.
It also says they are a crucial source of income for small and medium-sized organisations that don't have the resources and staff to compete for contracts. "Sometimes grant aid is the only suitable funding for the sector," said Kevin Curley, chief executive of Navca. "It must be sustained as part of the funding mix."
Vivien Hayes, director of the Women's Resource Centre, said: "Grassroots solutions to emerging problems would be impossible if grant aid were not available to enable women's organisations to set their own agenda according to need. The importance of grant aid for an independent voluntary sector cannot be overestimated."
The coalition, which also includes The Scarman Trust and Advice UK, the umbrella body for advice centres, has published a leaflet, Sustaining Grants, which it is sending to local authorities and other local statutory bodies.