Prime Minister John Key says Christine Rankin should continue in her role at the Families Commission as long as she can carry out her responsibilities to advocate for abused children.

Ms Rankin last night vowed to stay on as a Families Commissioner, despite her suitability being increasingly questioned after it was revealed she married her fourth husband soon after his previous wife committed suicide.

Ms Rankin went on television to deny having an affair with Kim MacIntyre before Wellington real estate agent Margo McAuley died in October last year.

She described Ms McAuley as a friend, and said her marriage to Mr MacIntyre at the start of this year "may seem unusual to outside eyes".

"Many think there was an affair. There was not," she told TVNZ's Sunday programme.

She criticised the "left" and the "gutter press" and said she would continue with the Families Commission role because she had "a great deal of knowledge, compassion and understanding".

Ms Rankin's personal situation and public response will bring further fire over her already divisive appointment.

Asked by the Herald afterwards if she had told Prime Minister John Key or anyone in the National Government of her intention to defend herself so publicly, Ms Rankin said, "That's none of your business", and hung up.

The Prime Minister also refused to comment last night.

Sunday newspapers yesterday reported details of Ms Rankin's relationship with Mr MacIntyre - including that they were filmed dancing together on election night at the National Party's SkyCity celebrations days after Ms McAuley's death.

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Ms McAuley's friends were quoted as saying appointing Ms Rankin to the Families Commission showed bad judgment.

Labour leader Phil Goff said he was reluctant to comment on personal issues, but the revelations raised concerns.

"People appointed to bodies like the Families Commission need to embody the values that those organisations stand for if they and the organisation are to have real credibility."

The Families Commission's aim is to speak out for all families to promote a better understanding of family issues.

Ms Rankin said she had been devastated by Ms McAuley's death "but I cannot tell my side of the story because to do so would be to expose details that are private to Margo".

She called her a "complex and difficult friend" and said that "emotionally, her marriage to Kim was over a very long time ago, and last year Kim decided to leave Margo".

Ms Rankin said the week since her appointment had been "vicious and destructive".

"I've really been treated quite appallingly, and I'm sick of it."

She dismissed Mr Goff's comments, saying, "Oh what a lefty he is."

The media had "stooped to new lows" and were largely worthless, with the exception of broadcasters Michael Laws and Paul Holmes.

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Ms Rankin had earlier said she had learned from her three failed marriages and would use her role as a Families Commissioner to promote the value of "Mum, Dad and the kids".

Mr Goff said it was not too late for Mr Key and the Government to abandon Ms Rankin's appointment, particularly given the increasing public division it was causing.

Last night, Social Development Minister Paula Bennett joined the PM in refusing to comment.

Both refused to say whether they knew about Ms Rankin's personal situation before she was given the Families Commission role.

The appointment, announced last Monday, is said to have been bitterly contested within the Cabinet.

Senior minister Simon Power yesterday refused to publicly endorse her when interviewed on TVNZ's Q & A, saying, "The Cabinet supported that appointment, therefore I did."

TVNZ political editor Guyon Espiner gave Mr Power another opportunity to say he supported it, to which Mr Power responded: "The Cabinet supported the decision. I'm in the Cabinet. That's the end of it."