Commenting on the polls which showed softening support for Mr Key as prime minister and for his Government, Mr Peters said he believed they were lagging indicators.
"Polls are frequently a reflection of a public change three months ago. It's already happened. I believe it will only worsen for this Government."
He claimed the Government was worried by to the growing awareness among New Zealanders that the economy was not being managed for their benefit.
"The Government talks about GDP growing but the New Zealand people are saying well it's not happening to me or provincial New Zealand.
"I've been through towns where there's all manner of shops closed and that is still the lifeblood and backbone of the country in terms of export growth and the answer has to be because so much of New Zealand is now foreign owned."
Mr Peters indicated foreign ownership of New Zealand assets including homes would be one of themes of his keynote speech on Sunday.
"The elephant in the room that no other party wants to talk about but which is one of the clear factors in the housing crisis in this country and in Auckland in particular, is unfocused immigration and external foreign ownership of New Zealand's realty assets.
"We're the party with the record on this and whereas in the past we've been accused of being racist and xenophobic, the truth is that some many of the commentariat actually write articles today knowing full well that all that is like reading a speech from New Zealand First."
The speech would also emphasise other issues where Mr Peters said other parties were now coming around to his party's views and policies including opposition to asset sales and support for compulsory retirement savings.
He was confident his party would increase its tally of MPs at the next election well into double figures.
"We know with enormous confidence that if we could get eight seats [in 2011] in a media shutdown, with no money and in a total blackout and outside Parliament, we can do a darn sight better with some of those features reversed in 2014 and we're going for broke to do it."
The conference would see discussion of how the party could improve its use of technology "to expand our loyal supporter base way beyond our paid up membership to the next tier".
However ahead of its conference the party was having trouble with technology, shutting down its social media presence following a complaint about youth wing leader Curwen Rolinson which sprang from claims that a member of Mr Peters's staff faked his CV.
Mr Peters said the claims were false, while party president Kevin Gardener was reluctant to comment, saying he didn't want the issue "mucking up" the conference.