But did say, "Any person presents their case as best they can and underline what they think is the best stuff and hope people don't see the bad stuff."
He believed the Green Party "played it very straight".
When a Party member was linked to damaging 700 National Party billboards in the 2011 elections, "we went straight to the media and told them everything we knew about it.
"I think people respected us for that," he said.
However Labour Party's disastrous campaign last year was a difficult pill to swallow.
"I think the Green Party kept it together.
"I think we did quite well but clearly Labour had some problems," he said.
He enjoyed working with Helen Clark and described it as "very interesting but challenging".
"I really enjoyed the interaction with her. She's really razor sharp and she was in a position of power," he said.
When asked if he had any "bad blood" with New Zealand First party leader Winston Peters, he admitted there was animosity about Mr Peters and the donation saga.
"That didn't put us on a good footing. But since then, we've had common ground on all manner of things.
"Even though we have had disagree about important issues," he said.
But he didn't mind. He simply put it down to the nature of the job.
"It's politics."
Dr Norman stepped down as Green Party co-leader in May this year.
He is now the executive director for Greenpeace New Zealand, replacing Bunny McDiarmid, who has been in the role for 10 years.
