The National Party has known for a couple of years about grievances regarding Jami-Lee Ross' conduct, and got one complainant to sign a confidentiality agreement, sources have told Checkpoint.

Checkpoint understands National Party President Peter Goodfellow facilitated a "gentlemen's agreement" with a woman who complained about Mr Ross' bullying behaviour. The agreement required her to not speak publicly about Mr Ross' conduct.

The complaint is believed to have been made a couple of years ago, which is when the agreement was also signed. Checkpoint has made multiple attempts to contact Mr Goodfellow today for a response.

National leader Simon Bridges was not the party's leader at the time. Speaking to media in Hawke's Bay today, he said he only learnt of allegations about Mr Ross' inappropriate behaviour in recent weeks, after the leak investigation was launched.

Newsroom has today reported the accounts of two anonymous women who said they'd had toxic sexual affairs with the MP and two others who said they'd been harassed and bullied by him.

"I'm gutted about the story and everything that it's about. I am in admiration of the courage of these women for what has happened here," Mr Bridges said.

"Within a day of learning about these things, I confronted Jami-Lee Ross about them and have made sure... he is no longer part of our caucus."

Meanwhile, one of the women included in the Newsroom investigation told Checkpoint she felt repeatedly threatened by Mr Ross, who she says told her her career would be over if she did not go along with what he wanted.

"I felt it was really wrong that he was even suggesting. I felt it was blackmail.

He would often call her from burner phones, which meant sometimes the numbers would appear as 'private' or a sequence of O.

"I got a call from Jami-Lee Ross and it was very dark, I didn't recognise his voice at all to begin with. It was on a number I didn't recognise…I picked up and said 'who is this'. As soon as I picked up he said 'why are you throwing away your political career'," she said.

Questioning who she was talking to, the caller identified himself as Mr Ross, then started speaking in his normal tone.

"He just kept saying 'why are you doing this, you're supposed to be a friend, I feel betrayed by you. You're basically asking me to go to war with you and your family."

She said her communication with Mr Ross continued to get "really dark", and she also fielded calls from Simon Lusk, who Mr Ross said earlier this week was a friend. Mr Lusk encouraged her to be on Mr Ross' side, because he was able to give her "a really strong career".

The woman, who Checkpoint has agreed not to identify, described the phone calls as "brutal", and said she was and is still scared of Mr Ross.

"I was extremely frightened…. I knew the circles he ran in."

Checkpoint also understands Mr Ross facilitated a trespass notice on a National Party member because they had disrespected his family.

Checkpoint has repeatedly tried to contact Mr Ross, who has also not responded, while Mr Lusk refused to comment.