Colin Craig is demanding a Conservative Party board member retract public comments he has made.
John Stringer spoke out this morning saying he was sick of a culture of confidentiality being used to cover up what he called abhorrent behaviour.
He also said he wrote a year ago with concerns about Mr Craig's working relationship with his former press secretary.
Colin Craig said Mr Stringer was wrong with many of the things he said, but could not say what.
"I've only seen the interview and there was a lot of content in it, I had not yet had the opportunity to work through piece by piece, but I have listened to it and I've taken already some preliminary advice.
"As I say I will be expecting a retraction slash correction of things he has said."
Mr Craig said he would announce on Monday action he would take against some media, which have reported what he called scurrilous material.
Right time for Craig to go, says Rankin
Christine Rankin, who campaigned alongside Colin Craig, says she is glad he has resigned and that it is right for him to go.
Mr Craig stood down yesterday, saying his resignation would allow the board to consider the party's leadership and direction.
Ms Rankin told Radio New Zealand she is hurt and disappointed and that she had been worried for a long time.
She said Mr Craig would never be honest and she was tired of confidentiality being used within the party.
She said that "it was over for Colin Craig", but she did not believe it was over for the Conservative Party.
Ms Ranking said she has no interest in the leadership.
Earlier today, Conservative Party board member John Stringer told TV3's The Nation the board had widespread concerns about Mr Craig.
He said it was completely untenable for Mr Craig to lead any party given accusations being made in the media.
Mr Stringer said the board was trying to hold Mr Craig to account and get him to discuss the matters.
He said he was speaking out because he was sick of a culture of confidentiality being used to cover up what he called "abhorrent behaviour".