Winston Peters has relinquished any chance to be a post-election kingmaker, pledging instead to prop up the major party which wins the most votes - but from outside the government.

Mr Peters confirmed yesterday that New Zealand First would not seek to be part of a coalition government after the election, saying there were too many "fundamental failings" in the policy packages of both Labour and National.

However, he said his party would "ensure that whoever the voters back to form a government, that government will have stability over the next three years".

NZ First would do this by offering a confidence and supply type of arrangement to the party which wins the most votes.

This would enable either of the major parties to form a minority government - an option NZ First hopes the party in front after election night might prefer over forming a coalition government with other minor parties.

It could, for example, work to sideline the Greens.

The counterbalance is that by guaranteeing to support the election-night vote winner and leaving United Future leader Peter Dunne as the only party whose support is up for grabs, NZ First has conceded what could be considerable post-election policy bargaining.

But Mr Peters' position, outlined to a packed hall of about 350 people in Rotorua yesterday, is a concession that the party cannot once again afford to be seen playing off different parties "king-maker style"' after the election.

It hopes its stance will revive poor poll ratings, which have recently threatened to tip the party out of Parliament altogether

Mr Peters wants a different, effectively watered down, type of confidence and supply deal to the one between United Future and the Labour-led Government.

Under his plan, NZ First would abstain on confidence and supply votes - effectively reducing the total number of votes required to pass such a motion in Parliament.

Critically, however, he is promising a confidence and supply vote in favour of the minority government if need be.

This is important because if National, for example, won more votes than Labour but only by a slim margin, and all the minor parties voted against a National minority government on confidence and supply, NZ First's "yes" vote would be required to keep the government from collapsing.

NZ First would not guarantee a government support on any other votes.

Mr Peters' support would come at a price - but he continued to steer away from any absolute "bottom lines" yesterday, saying the phrase was neither "co-operative nor positive".

Like most of the smaller political parties, the party will be assessing its post-election bargaining power - indeed whether it has any - before taking too many negotiation positions.

Mr Peters said the party's first priority was the Golden Age Card for senior citizens and it would seek accommodation on its immigration, law and order, Treaty and economic policies. The position means Mr Peters' ability to negotiate policy wins from the cross benches could depend entirely on how the votes fall on election day.

National is getting cosier with United Future and until now would probably have shunned Mr Peters if it could - but United Future is not expected to win more than a few seats.

Labour has said NZ First is second to last on its list and is talking coalitions with the Progressives and the Greens.