More than 250 charity chief executives have signed a letter to the Prime Minister, David Cameron, requesting a meeting to discuss how charities can contribute to his big society agenda.
The letter, which was sent by chief executives body Acevo last week, calls for the government to send "an early, electrifying signal from the top that the way Whitehall deals with our sector needs to change".
As shadow Chancellor, George Osborne told the Acevo-Conservative Party summit in March that the Tories had ambitious plans to increase charities' involvement in public services if they came to power.
The subsequent election and the party's vision of a big society has further increased charities' hopes of providing more services in areas such as welfare, prisons and health.
The letter, whose signatories include Stephen Bubb, chief executive of Acevo, Kevin Curley, chief executive of local infrastructure group Navca, and Jackie Ballard, chief executive of the RNID, says: "We are writing to ask that, from the very start, you work with our sector as real partners and spark a step change in the way government and civil society leaders relate.
"That might mean a third sector leader on every departmental board; it might mean an advisory council of third sector leaders at the heart of government; it might mean a commission on the future of government/third sector relationships; it might mean similar commissions for each of your departments; it might mean a taskforce with the Treasury on transforming public services."
It asks Cameron to meet a delegation of charity leaders to discuss these ideas and other ways forward.