Stuart Etherington, chief executive of the NCVO, is expected to use his speech at the umbrella body's annual conference today to urge politicians to respect voluntary organisations for their campaigning as well as their service provision.
Oliver Letwin, due to write the Conservative manifesto for the forthcoming general election, told the NCVO's campaigning conference last month he regretted that "so much of the effort of some parts of the voluntary sector is devoted to campaigning".
But Etherington is expected to criticise the "unhelpful debate" that tries to separate campaigning from service delivery, and will say that both are "legitimate and vitally important roles for our organisations".
He is also expected to warn charities about the risks of public service delivery. "If done well, contracting means we have a greater influence over what services are provided, and how they are provided," he is expected to say. "But if it's done badly, our sector simply becomes a mechanism for delivering a government agenda."
Etherington is also expected to urge charities to seize opportunities thrown up by the likely spending squeeze and accompanying reforms in public services. Last week, the Tories unveiled plans to allow public sector workers to form cooperatives.