He said the so-called rock-star economy was actually on the rocks.
"If this is as good as it gets, then it doesn't matter who the next Prime Minister is.
"A vote for New Zealand First is a vote for New Zealand First and not for any other party."
The Campbell Live debate was more of a timid discussion around the dinner table at Auckland's Grand Harbour Restaurant, as subjects traversed the Maori seats, the minimum wage, and tax policy.
Each leader was asked who they wanted to be next Prime Minister. Mr Craig, United Future's Peter Dunne, and Act's Jamie Whyte all said John Key, while the Green's co-leader Metiria Turei and Internet Party leader Laila Harre opted for David Cunliffe.
Maori Party co-leader Te Ururoa Flavell said he was "not fussed" and could work with either, as long as the relationship helped Maori.
Mr Craig took a dig at Mr Peters:
"Every single person gave an honest and direct answer except one ... People are looking for a safe pair of hands, and for people they can trust."
Mr Peters retorted that the Conservatives had simply stolen all his policies. "Imitation is the sincerest form of flattery."
After the dinner, Mr Peters said it would be irresponsible to lay his cards on the table without "all the facts".
"This has been the most astonishing campaign ... and I believe in the next 16 days there's a lot more to come yet."
He did not think he would lose any votes over it.
Nicky Hager's book Dirty Politics was only mentioned when Mr Peters said he believed the "explosive" claims in the book were true.
"The left-wing didn't write the emails. The National Party did.
"We need to restore political integrity."
The parties argued over the Maori seats, which Mr Flavell said was always a hot topic every election, when issues of "kai on the table", tertiary education and home insulation were more important.
Mr Peters accused Hone Harawira of destroying the Maori seats' integrity in a "deal with the German who should not be here in the first place".
The dinner started with party leaders talking about what they thought was the most important issue.
Mrs Turei said it was child poverty, while Ms Harre said it was young people and helping them into education, training, or work.
Mr Dunne said it was about helping families and parents, while Dr Whyte said it was a dynamic economy, fueled by a low company tax rate to drive investment and productivity.
Mr Flavell said family violence was a major issue in three Maori electorates, and Whanau Ora was his focus.
The leaders took a moment to giggle at Dr Whyte, who was previously embarrassed when he revealed he did not know what Whanau Ora was.
Read more:
The Herald's top political correspondents pick their winners from the minor party leader's debate.