The National Council for Voluntary Organisations has invited third sector leaders to a summit to consider the impact of the new coalition government on charities.
Stuart Etherington, chief executive of the umbrella body, said: "It will be imperative that our sector works together to create an environment in which voluntary organisations can thrive."
He said the NCVO looked forward to helping new Prime Minister David Cameron refine his ‘big society' vision and "clearly set out the role our organisations can play within it".
Etherington added: "It is important that spending plans recognise the role that voluntary and community organisations play across many policy areas."
Chief executives body Acevo will write to Chancellor George Osborne requesting a meeting between Treasury officials and Acevo members to discuss ways of increasing the voluntary sector's role in delivering public services.
Stephen Bubb, chief executive of Acevo, said he wanted to press ahead with this despite concerns that the Tories had kicked their big society agenda into the long grass after it proved unpopular.
"The Conservatives have made such a big thing about the big society and broken Britain they are going to have to do something about it and they can't do it without the sector being involved," said Bubb.
"The reality is they have made this a core platform, so whatever name they give to it we can capitalise on it."
Bubb said a progressive alliance involving Labour, the Liberal Democrats and the nationalist parties might have "compromised the sector" by giving too much power to union-supporting elements opposed to wider voluntary sector service delivery.
Other key priorities, he said, were establishing the Big Society Bank and convincing the Tories to abandon their "bizarre" plans to redirect money from the Futurebuilders loan book towards its big society plans.
Louise Richards, director of policy and campaigns at the Institute of Fundraising, said the organisation would lobby for a simplification of the process of claiming Gift Aid, which she said the Conservatives and the Liberal Democrats had both agreed to before the election.
"We want to engage quickly with ministers at the Treasury and the Office of the Third Sector, once they are in place," she said.
"Our first target will be extending transitional relief on Gift Aid for another year after it runs out in April 2011. Then we'll look at reducing the administrative burden of Gift Aid, and in the longer term we'll talk to ministers about whether a composite rate could be introduced."
She said she was not sure whether the Gift Aid forum set up by the previous government would continue, but that the institute had set up a Gift Aid working party that included representatives from charities as well as Acevo, the NCVO, the Charities Aid Foundation, the Charity Tax Group and the Charity Finance Directors' Group.
Neil Cleeveley, director of policy and communications at local infrastructure group Navca said it wanted early discussions with the new Government to ensure it remained committed to local voluntary action.
"In the run-up to the election we were encouraged by the support all parties gave to local voluntary action," he said.
"Our concern is that now these issues could be pushed to the back seat as the Liberal Democrats and Conservatives focus only on the issues aimed at reassuring their MPs."