The perception of many in the voluntary sector is that a Conservative government will not be pro-charity, the Directory of Social Change has warned.
Debra Allcock Tyler, chief executive of the training and support charity, said that after the Tory election victory it was crucial that charities continued to represent the needs of their beneficiaries to both the government and opposition parties.
"Whether it is true or not, the perception of many in our sector is that a Tory government is not pro-charity," she said. "People are concerned about charities' right to campaign and speak out, public spending cuts that affect our beneficiaries and whether we have genuine access to policymakers."
She said that the sector would have to work harder to convince the new government of the vital role of charities in society and that they could not be ignored or silenced.
"We need to persuade them to rethink the excessive focus on social investment and contracting, and look again at the crucial role of grant funding," she said.
"We also have to argue for continued efforts to support charitable giving, volunteering and social action - and tell the new government clearly what will help do this and what won't."
Sir Stuart Etherington, chief executive of the National Council for Voluntary Organisations, said it looked forward to working with the new government on the issues that related specifically to charities and volunteering, "including a sensible resolution to the problems brought about by the lobbying act, a shift of gear on our involvement in public services, taking forward the draft Protection of Charities Bill and implementing manifesto proposals for increasing employee volunteering".
Peter Lewis, chief executive of the Institute of Fundraising, said he wanted the new government to help charities to fundraise better.