Gareth Morgan is set to go to the High Court to try to get The Opportunities Party into a TVNZ debate on Friday night after the network said it was not polling high enough to warrant a place.

A spokesman for TOP would not comment, but the party is expected to lodge an application for judicial review on Wednesday of TVNZ's decision to exclude it from the debate between the minor party leaders on Friday night.

It is likely to seek an urgent interim decision to get it into the debate.

1News' political editor Corin Dann said on the programme tonight that it was longstanding policy not to include parties that were outside Parliament in election debates unless they had reached three per cent in at least one of the most recent 1News Colmar Brunton polls. TOP had not reached that threshold.

It is not the first time a minor party has taken such action - and precedent is on TOP's side.

In 2005 the High Court ordered TV3 to include United Future leader Peter Dunne and then Progressives leader Jim Anderton in its debate after it tried to exclude them.

Justice Ron Young said excluding them was detrimental to New Zealand's democracry.

TV3's then head of news Mark Jennings objected to what he described as judicial interference in editorial decisions, and said it set a dangerous precedent.

It is understood TOP has also taken umbrage at being excluded from candidates' panels on other TVNZ shows such as Backbenches and a youth debate due to be hosted by Jack Tame next week. Only Te Karere has invited the party on.