The campaign, Real Power for Communities, warns that some councils will be reluctant to hand more power to local voluntary and community groups despite provisions in the legislation for them to do so.
"Our view is that some local authorities are not keen to hand away their powers," said Kevin Curley, chief executive of Navca. "The bigger ones might lobby MPs directly, asking them to amend the bill so that they can keep some of their powers, and the Local Government Association might become involved in this as well."
Curley said the new campaign aimed to encourage community groups to lobby their MPs to protect the contents of the Localism Bill. "They'll have to show MPs why it's important for them to play a bigger role at a local level," he said.
He added that the reluctance of some councils to let community groups use empty council-owned buildings was an example of councils being unwilling to devolve power.