Former Conservative Party board member John Stringer alleges Colin Craig was involved inappropriately with more women than just his press secretary Rachel MacGregor.
Mr Stringer has given evidence in the defamation case Jordan Williams is taking against Craig.
Mr Williams is being sued by Craig for more than a million dollars, and he is countersuing Craig and his wife.
Mr Stringer wrote around 80 blogs about Craig, one suggesting women other than Ms MacGregor would be stepping forward about Craig's impropriety.
When he was pressed on this by Craig's lawyers at the High Court in Auckland on Monday, he said he'd seen court documents about one of Craig's employees at Centurion, whose lawyer approached a media outlet.
"[The woman] expressly said that she would be prepared to testify in court about matters similar to those of Ms MacGregor related to Mr Craig - that's how I became aware of other women, plural," Mr Stringer said.
Mr Stringer accepted that at the time of writing he hadn't seen the court documents.
He also talked of a third woman but accepted he had no factual foundation for that claim, and Craig's lawyer says his client will deny both claims.
Mr Stringer says there was so much concern among board members about Craig's relationship with Ms MacGregor that they used a chaperone to accompany them whenever they were together.
The board had been asking questions about the relationship for years, Mr Stringer said, and the woman asked to chaperone was annoyed at having to do this as it took her away from other work for the party.
However, Mr Stringer said: "It was necessary to avoid, to use a biblical phrase, the appearance of evil".
Mr Stringer said that Craig dismissed any concerns raised by the board, and said that any allegations of moral impropriety were "scurrilous, baseless, false and just wrong".
Mr Stringer has claimed that Craig created an almost cult-like culture of confidentiality in the party.
He said Craig disciplined, harassed, and harangued members who disagreed with him and left the party. He also publicly denigrated them in updates from the party.
"I believe Mr Craig polluted what had been a happy and functional party, which descended into acrimony, suspicion, and paranoia," Mr Stringer said.
Mr Stringer was mentioned in a leaflet along with Mr Williams that Craig released at a news conference, making 1.6 million copies.
He said there was no strategy to defame Craig, and told the court it wasn't dirty politics. He said actions against Craig were about losing all confidence in him and intending to roll Craig as Conservative Party leader.
"I, along with many others, was stunned that the leader of a conservative movement was writing secret love letters to his press secretary while telling us she was obsessed with him and nothing was going on," he said.
"It wasn't dirty politics or a strategy - it was us losing all confidence in him and wanting to roll him as leader."
At one point Mr Stringer texted Mr Williams as the party began to disintegrate, saying: "Time to carpet bomb the Colin Craig cult compound. Make sure this clown doesn't come back."
Later in court, Mr William's mother, Megan Williams, broke down as she told a court she felt sick and devastated over the words written about him in the 'Dirty Politics' leaflets.
Through tears she told a jury her son was not like what the leaflets said, and that he was a good son.
"Jordan has always been a political animal. And everybody blames me for that."
She said she believed Craig had gone after Mr Williams for revenge.
"I thought Colin Craig was a really nice person. I couldn't understand why he would have done this," she said.
"What's happened is now of course, my friends don't come and say to me, you must be very proud of him."
While his mother was speaking, Mr Williams was unable to hold back his tears, momentarily leaving the court room while she was giving evidence.