The Save Radio New Zealand campaign group has held a meeting in Wellington to discuss what it calls a manufactured funding crisis, aimed at strangling the public broadcaster.
About 150 members of group, which began on a social networking website and now has almost 20,000 members, were at the meeting.
The group says an independent review has found Radio New Zealand is 20% underfunded, and it says suggestions of cutting costs by allowing commercials or sponsorship are undemocratic.
Filmmaker Gaylene Preston, who was among those at the meeting, said she feared stories about New Zealand life will be lost if Radio New Zealand goes down the commercial path.
Green Party broadcasting spokesperson Sue Kedgley says it's fundamental to a democracy to have a broadcaster that is free to speak out, without censorship from advertisers.
The Labour MP for Wellington Central, Grant Robertson, says Radio New Zealand has been tightening its belt for decades and should not have to cut its budget further.
Broadcasting Minister Jonathan Coleman was not at the meeting, but said in an interview that Radio New Zealand needs to live within its means.
Ms Kedgley says the Government has invented a spending crisis to justify commercialisation but the minister reiterated there is no secret agenda to privatise Radio New Zealand.
Radio New Zealand's board will report to the minister by the end of this month on how it plans to cut costs.