The Act Party is in danger of splitting apart again over an advertisement critics have called racially divisive and backward-looking.

But leader Don Brash, who denies he is racist, says more party members agree with the advert than are offended by it.

All other political parties have distanced themselves from the advert - which ran in the Weekend Herald under the headline "Fed up with pandering to Maori radicals?" - and the Maori and Mana parties have called it offensive and wrong.

It was designed by marketing guru John Ansell, who resigned while calling Act "cowards" and "bedwetters" for not using other adverts, one of which used the term Apartheid Aotearoa.

Yesterday, Dr Brash said the decision to run the advert was made by a select few.

"It didn't go to caucus. Clearly [parliamentary leader] John Boscawen was involved, and other people. There will be some people in the party who won't have liked the ad. My own view is that more people will like it than not like it."

Asked if the strategy could lead to renewed factions in the party, he said: "Whenever you take a strong position on anything, there will be people who don't like it. I would obviously regret it if anyone felt so strongly about it that they would have to leave."

Former Act MP Deborah Coddington called Dr Brash an "old racist".

"Don Brash obviously thinks that if he screams this racist stuff louder, it will get him further up in the polls," she told Radio NZ.

"I know there are a number of people in the party who are horrified ... just appalled."

Last night Mr Brash denied his party was guilty of "Maori bashing" in a debate with Maori Party leader Pita Sharples.

"It reflects a very widespread concern among New Zealanders that we are going down a track that is very dangerous for our future," he told Maori TV's Native Affairs.

"The only sound basis for a modern democratic state is one where every citizen has the same legal rights ... successive governments have gradually sought to appease Maori radicals who want to create preferential rights for Maori."

Dr Sharples said his party sought opportunities for Maori which would take them forward in a united country.

"I remind him of the tyranny of the majority. Under one person, one vote we haven't done so well as Maori," he said.

"We want to change the situation where one lot is under-achieving within a system where we have plenty for all in this country."

Dr Sharples challenged Dr Brash to go door-knocking with him in his electorate.

"Then you will see who is privileged ... we have to have measures which ensure equality."

- additional reporting by NZPA