Prime Minister John Key and Labour leader Phil Goff won't be sharing the stage with smaller party leaders in the lead up to this year's general election.
In 2008 then Prime Minister Helen Clark and Mr Key refused to participate in debates alongside minor party leaders, despite doing so in previous years.
In that election the two leaders' offices agreed to provide a united front against the TV networks in agreeing only to head-to-head debates between them.
The leaders were then able to spend more time pressing their cases in a more presidential style without having to share the stage with others.
Mr Key confirmed this morning he would not agree to appear with the other leaders.
He said most New Zealanders would vote National or Labour and it made sense for viewers to get the chance to consider their potential prime ministers.
"The leaders' debate is an interesting opportunity for New Zealanders to get a sense of who they want to see as the next Prime Minister of New Zealand and practically, at the moment, the only two contenders for that job are Phil Goff and myself."
He did not accept that undermined MMP and said his Government had worked well with the Maori, ACT and United Future parties. A separate debate for those parties was good for them, he said.
Mr Goff said he would not appear in debates where Mr Key did not.
"If he's not going to be there, then that takes away the main debate between the two major parties. He should be there," he said.
Mr Goff said there would be a lot of opportunities for election debates and he had committed to five or six.
"Interestingly to date, John Key has not engaged in any direct debate, he's turned them down."
Mr Goff said he did not know if his staff had discussed the issue with Mr Key's office.
"I've made the point quite clear -- on any platform that John Key is going to be up there, I'm ready to debate with him over issues that really matter to New Zealanders."
In 2005 there was a row when TV3 tried to exclude United Future leader Peter Dunne and Progressive Party leader Jim Anderton from a debate on MMP.
The network said eight leaders was too many, but Mr Dunne and Mr Anderton went to court and TV3 had to let them take part.