The Coastal Coalition wants Prime Minister John Key to remove Attorney-General Chris Finlayson from foreshore and seabed repeal bill duties after he attacked the group as "clowns" and "profoundly sickening".
Spokeswoman Muriel Newman said his attack - in the midst of the select committee process - was so personal it showed he was not being open-minded as a minister in charge of a bill needed to be.
She was writing to the Prime Minister yesterday, before her appearance today before the Maori Affairs select committee in Whangarei on the Marine and Coastal Area (Takutai Moana) Bill.
Maori Party dissident and Te Tai Tokerau MP Hone Harawira and his electorate committee are also making submissions today against the bill, which was proposed after negotiations between National and the Maori Party.
Mr Finlayson took to the road last week in a series of meetings to counter what he called mistruths by the Coastal Coalition.
Speaking to the Herald about the meetings, Mr Finlayson said: "I'm not going to be beaten by these clowns.
"I'm not going to be beaten by people who think the Phoenicians and Vikings were here first.
"This was [supposedly] a veritable crossroads of the ancient world. Phoenicians were here, Celts, Vikings, you name it, they were all here except for the Maori."
Dr Newman, a former Act MP, said she did not believe those views.
Mr Finlayson had dredged them up from something she posted on her website in 2006, in which she was commenting on a feature in the Economist on new evidence about the discovery of the world and which mentioned New Zealand.
"All I did in that article was raise the issue. He is essentially hitting out with pretty vitriolic attacks, bullying people, intimidating them, trying to shut them up, playing the man, not the ball. I think it is all a sign that he has lost the plot."
She said it was vital that the minister in charge of the bill remained objective and open-minded.
"I just don't think he is in any fit state to do that objective-process bit."
She believed the National Party was bleeding support over the issue.
"I think what they did was they totally under-estimated the strength of attachment that people have to the public foreshore and seabed.
"The coast is part of who we are as New Zealanders."
The Coastal Coalition was made up of thousand of ordinary New Zealanders including many National Party members.
"When he insults me and the Coastal Coalition he is insulting a good many National Party supporters."
The coalition has funded a large number of Q and A advertisements in newspapers.