National Party leader John Key has warned that Winston Peters could hold the country to ransom if he holds the balance of power after the election.
The New Zealand First leader says he will not do a deal over confidence and supply with Labour or National if his party is returned to Parliament after 26 November.
New Zealand First has been rising in the polls; on Friday the Herald-Digipoll had the party at 4.9%, just shy of the 5% it needs to enter Parliament.[image:3813:half:right]
Mr Peters says if his party does get in, it will hold the major parties to account from the opposition benches.
During campaigning in Auckland on Sunday, John Key said that would mean there would be a risk that a general election could be forced on every Budget or every major issue, and raises the prospect of three years of political instability.
"What Winston Peters is saying to New Zealand is that on every budget, on every issue, there could be a general election.
"How can New Zealand govern itself over the next three years - which is likely to be a volatile period in the world economy - when at any stage the whole government can be brought down by Winston Peters?"
Mr Key also questioned whether Mr Peters would stick to his word, saying the New Zealand First leader said the same thing before the 2005 election before signing up with Labour.
But Winston Peters urged John Key not to panic, saying he should accept the will of the voters - even if it is not the result he would like.
Mr Peters believes his party will get much more than the 5% support required.