As far as protests go, it wasn't a big one.

But the MPs who joined about 50 protestors outside state parliament on Thursday were there to make clear that on any bid to force council mergers, it was the government – not them – lacking the numbers.

"If there is legislation and it comes up to the upper house at the moment, you would have to say from today they're in real deep doo-doo," the opposition's local government spokesman Peter Primrose said.

Representatives from each of the minor parties joined Mr Primrose at the launch of the "Save Our Councils Coalition", or SOCC, comprising councillors and community groups opposed to the state government's push to reduce the number of NSW councils.

"Forced amalgamations are so unpopular, so anti-democratic, that everyone from the Christian Democrats to Labor to the Shooters and the Greens are standing together to oppose them in Parliament," Greens MP David Shoebridge said.

Shooters and Fishers MP and Ashfield resident Robert Borsak said the state government's Fit for the Future process, which requires councils to either put forward a merger proposal or justify to the Independent Pricing and Regulatory Tribunal (IPART) why one is not necessary by June 30, "was a flawed process from the start".

"The whole thing's only ever been set up as a con to get around their failed planning bill that we knocked over," Mr Borsak said.

Independent MP Alex Greenwich said "it's not clear" whether the state government could force councils to merge without requiring new legislation.

Mr Primrose said the government should hit the "pause button" on the reforms until a parliamentary inquiry considered this and other issues.

"There's a whole range of really good ideas which have been overlooked in this whole debate," Mr Primrose said.

SOCC is calling for mergers only to proceed if they first win the backing of their communities through a referendum.

"My challenge to Minister Toole, who always seems very quiet and we have a difficulty arranging any meetings with him at all, is if you reckon this is on, then put it to a referendum and let's settle it once and for all," Holroyd mayor Greg Cummings said.

The SOCC's call was backed by Christian Democrats MP Fred Nile, a ratepayer of Warringah, which is seeking to merge with Manly and Pittwater.

"Any amalgamations will take away the local emphasis, it will just get bigger and bigger," Mr Nile said.

"Local councils would become controlled then by the Labor Party or Liberal Party."

Local Government Minister Paul Toole, who has repeatedly refused to rule out forced council mergers, said councillors needed to act in the best interests of their communities "not out of self-interest".

"Until [IPART's] report is received it is premature to comment on what will happen next," Mr Toole said.

Meanwhile, Waverley Council decided on Wednesday to merge with neighbouring Randwick – although the vote is the subject of a rescission motion seeking to overturn it.

Its mayor, Sally Betts, said the council could not meet the state government's "scale and capacity" requirement with its population of about 70,000.

"We voted to merge because we believe we need to take control of our future and be part of the decision making process," Cr Betts said.

Randwick's mayor Ted Seng welcomed Waverley's decision.

"I'm pleased to see Waverley Council standing up for their residents and making this tough decision," Cr Seng said.