On the eve of his party's annual conference in Brighton, Opik told Third Sector that organisations should cooperate on soliciting funding from the state.
"The third sector needs to speak with one voice," he said. "There is a great deal of squabbling. Organisations compete aggressively for the same limited funding.
"I would like to see the National Council for Voluntary Organisations act as a facilitator to encourage a more strategic approach to funding in the sector."
Opik, currently formulating the Lib Dems' policy on social enterprise, also wants to tackle what he calls the "albatross of administration that is a disincentive for local voluntary action".
He said: "Litigation is an enormous cost for the sector. Individuals are disinclined to volunteer because they fear they might get sued. I would like to see a genuine regulatory impact assessment to see what legislation does not work."
The NCVO will unveil a new approach to the party conferences at the Lib Dem conference, which begins at the weekend. The umbrella body's fringe events at all three conferences will concentrate on allowing small charities to present their campaigns and concerns to politicians. Small charity recipients of an NCVO bursary scheme will attend the Lib Dem conference.
John Low, chief executive of the Charities Aid Foundation, will speak at the conference on "incentivising the rich to give".
A spokeswoman for CAF said the foundation wanted to start a debate about encouraging giving by high-net-worth individuals but said there was disagreement in the sector over whether a tiered system of tax incentives to promote giving was fair.
Environmental charity Groundworks is hosting a fringe event at the conference on whether personal aspiration is killing communities.
Graham Duxbury, director of development at Groundworks, said: "We want to start a discussion about how you promote community policy that supports personal goals but builds incentives for people to work for the common good."