Newly-appointed Families Commissioner Christine Rankin rejected calls to turn down the position on Monday, saying she will not be intimidated.
The controversial former Work and Income chief executive has been appointed as one of seven commissioners, and will work in the role part-time from 1 June.
The Government also appointed Parents Incorporated chief executive Bruce Pilbrow on Tuesday. They replace outgoing commissioners Sharron Cole and Lyn Campbell.
Ms Rankin was heavily criticised by the Labour Party in the late 1990s for creating a culture of extravagance at the department. She eventually left Work and Income during the previous Labour-led Government's first term in office.
More recently Ms Rankin spoke out strongly against the child discipline law, the so-called anti-smacking legislation, which was supported by the Families Commission.
Political leaders on Monday criticised her appointment, including United Future leader Peter Dunne, who fears it could spell the end of the commission.
Mr Dunne, who is also Revenue Minister, says Ms Rankin is controversial, divisive and grossly unsuitable for the appointment.
Mr Dunne says he was not properly consulted by the National Government and Mr Rankin's appointment was bitterly contested within the Cabinet. He says Ms Rankin does not enjoy sufficient political support to make her appointment tenable, and believes she should reject it.
"This is a wrong appointment and I think it will prove to be very damaging."
But Ms Rankin told Checkpoint on Monday that she will not be intimidated by Mr Dunne's "bullying" and has every intention of doing the job.
"I'm very passionate about the state of New Zealand children and families and I look forward to my role ... I think the commission needs to get some results for New Zealand families and I hope I can contribute to that happening."
Ms Rankin says it is too early to say what changes she would like to see, but admits she does have some concerns.
"It appears to me that the Families Commission does a lot of research. Well, at some stage we have to take action with the research that we've got ... Perhaps they do lobby the Government in terms of all of the research ... I need to wait and see."
Appointment political payoff - Labour
Labour Party deputy leader Annette King says Ms Rankin's appointment is political payoff for doing the bidding of the National Party, and says she is not an appropriate choice, given her previous record.
Prime Minister John Key rejected that criticism, saying Ms Rankin's views differ from those of National's on several issues, but she has a strong interest in children and will speak strongly on that issue.
Labour says the Cabinet was divided over the appointment - an accusation the Government also rejects.
Mr Key is refusing to say whether the Cabinet had discussed Ms Rankin's previous roles when deciding on her appointment.
Lobby group Family First lobby praised the appointment, saying she will bring diversity and a down-to-earth approach to the commission.
Family First national director Bob McCoskrie says although Ms Rankin has been divorced several times, he believes this will not affect her ability to be an advocate for families.
But Child Poverty Action Group is concerned about the appointment, saying Ms Rankin has a poor record of advocating for families.