The pledge comes in the foreword of A Stronger Society: Voluntary Action in the 21st Century, the party's first comprehensive list of policies for the sector, which was launched yesterday (Third Sector Online, 3 June).
"The time has come for us to think of the voluntary sector as the first sector," Cameron writes. "Not just in recognition of the historical origin of the public services and institutions we rely on today, but as the first place we should look for the answers that neither the state nor the market can provide."
Cameron describes the delivery of public services by voluntary organisations as a "pivotal and divisive issue, presenting the sector with enormous risks and opportunities". He does not come down on either side of the debate, he says, out of respect for the "sheer variety of the sector".
Among the 20 Conservative pledges are proposals to set up an Office of Civil Society, protect lottery funds from government raids and strengthen the Compact.
Greg Clark, the shadow charities minister, told Third Sector that the Compact should be enforced. "We want to consult the sector on what the sanctions will be," he said. "You want to avoid it becoming too legalistic. It's about making sure that it is abided by while avoiding it being a difficulty for charities."
Clark also emphasised that a Conservative government would work with charities to encourage volunteering as "a social norm", and all central government employees would be given eight hours a year volunteering time to back the move.
"It is important that government encourages people to think about volunteering," he said.