But Mr Nash last night denied he'd commissioned the report, telling Hawke's Bay Today that he was "Labour to the core," and the email, though genuine, was the result of a misunderstanding between him and Mr Johnson.
He said he had been approached by his friend, Wellington property investor Troy Bowker and another man "Ned" who he refused to identify, about starting a new political party, but turned them down.
The pair nevertheless commissioned the report from Mr Lusk without his knowledge.
Mr Lusk eventually told them their plan was not feasible. "I told Rob what happened and he thought I commissioned the report."
Mr Nash confirmed: "Rob will stay on as my campaign manager and he will run my Napier office."
He said Acting Labour Leader David Parker had obtained a copy of the email and rang him about it on Sunday, the same day he decided to pull out of Labour's leadership race, but it wasn't a factor. "In fact, I'd made the decision earlier and this email had absolutely no bearing at all."
A spokesman for Mr Parker told Hawke's Bay Today last night that he wasn't commenting on the matter, and all questions were to be directed to Mr Nash.
In a statement to 3News, Mr Lusk said Mr Nash "has not paid me". Mr Johnson could not be contacted for comment last night.