New Zealand First leader Winston Peters claims his own polling shows he is set to win far more votes - 20 percent - in the coming election than media polls, he said were fake.

Photo: RNZ / Benedict Collins

RNZ's most recent poll-of-polls had New Zealand First sitting at 8.7 percent.

But Mr Peters said the media's polls were fake - and his own polling put his party's support far higher - closer to 20 percent.

"I've got the statistical evidence to prove it, I don't know why the media carry on with their mindset and keep on boring people witless with scenarios that are not going to happen."

Mr Peters has electorate offices in Kerikeri, Kaitaia and Dargaville and two more outside Northland's boundary.

"For the first time people up here are hearing the truth - for the first time here people are hearing what's going wrong with central government - they're not believing the National Party's bull anymore," he said.

"They know that the funding here for all those things that were promised by the National Party has not happened - they have not built one metre of the super highway from Puhoi to Warkworth - that they have not built one metre of any of those bridges at all," Mr Peters said.

The National government promised to double-lane 10 one-lane Northland bridges during the by-election campaign.

Mr Peters said locals thought it was a joke.

"They seriously ask me, 'Winston where are those 10 bridges?'

"And I say 'well, they've forgotten seven for a start and not one has started'."

Either a 20 percent or 9 percent result suggests Mr Peters could be the kingmaker again - with the opportunity to choose a coalition partner to form the government.

In a crushing by-election win in March 2015 Winston Peters - the self-proclaimed 'Force for the North', became the MP for Northland, breaking National's hold on the seat.

Mr Peters' plan was to retain Northland and add the neighbouring electorate to the New Zealand First basket in September's election.

"We're going to win this seat and we're going to win Whangarei as well - that's what's going to happen in 2017."

It's widely tipped Mr Peters' good friend, the former Labour MP Shane Jones, will stand for the party in Whangarei but Mr Peters said he couldn't confirm that.

"I can't tell you who's going to put their names forward and this is a matter that is handled by the party machine and not me."