"One really has to question what Parliamentary staff are doing being involved in raising money and trying to get votes for a political party when their job is obviously towards Parliamentary Service", Mr Horan said this afternoon.
Asked whether he understood that Parliamentary Service paid all of Mr Dawson's salary or that he received some pay from the party, Mr Horan said he didn't know.
"That's one of the questions that's fair to be raised."
Mr Horan's latest attack comes after he raised questions around Mr Peters' interest in a race horse which was not declared in the MPs' Register of Pecuniary Interests, and allegations of bullying of staff by another NZ First MP.
A spokeswoman for NZ First Leader Winston Peters said he would not comment on Mr Horan's latest allegations.
Mr Horan told reporters he wasn't attempting to destroy Mr Peters' political career; neither was he engaging in a personal vendetta.
"I'm not out to destroy anybody. I despise the act of hypocrisy, I despise the act of bullying and I'm standing up against the biggest bully in Parliament. What I'd like to see happen here is the rules are followed, that the hypocrisy ends in this Parliament and we get on with the important business of trying to do what MPs do, which is supposed to be helping people and making the economy grow."