Changes to the MMP electoral system could be back on the table including the controversial coat-tailing provision, Deputy Prime Minister Winston Peters has indicated.

The coat-tailing provision allows a party to dispense with the 5 per cent threshold if one of its candidates wins an electorate seat.

New Zealand First, The Progressives, United Future, Act and the Maori Party have all benefitted from the rule at various elections since MMP was introduced in 1996.

If a party does not win an electorate seat, it must win at least 5 per cent of the party vote in order to get any MPs.

Advertisement

Peters told TV1's Q + A he would be open to the last MMP review being revisited.

The previous Government had thrown the last review "in the rubbish bin."

Asked if he would be open to the review being reconsidered, he said that was a "marvellous suggestion."

"I might put that to my cabinet colleagues and after consultation, if they agree, we might do that."

Following a referendum in 2011 confirming MMP as the preferred system, the Electoral Commission reviewed MMP in 2012.

But in 2013 the National-led Government of the day declined to promote change on the basis there was not a majority in Parliament to pass the review's recommendations.

Its recommendations included ending the one-seat threshold, reducing the threshold from 5 per cent to 4 per cent, and reducing the overhang provision, which allows the Parliament to have more than 120 MPs in some circumstances.

Peters' New Zealand First Party, Labour and the Greens – all in Opposition at the time – wanted to abolish coat-tailing (also known as the one electorate seat threshold.

They now make up a majority of Parliament. However they do not agree on reducing the threshold to 4 per cent. Only Labour and the Greens supported that. New Zealand First opposed lowering it at the review - and still does according to Peters.

"If you are not worth 5 per cent, you shouldn't be in Parliament," Peters said on Q + A.

Act leader David Seymour said he would never be opposed to people talking about things but it should not be done simply for the parties of Government to advantage themselves.

"It is completely in the Government's interests to drop the threshold to 4 per cent and have no coat-tailing because neither of the Coalition or confidence and supply partners are going to win a seat realistically and they are going to be in some danger of dropping below five per cent."

The Greens won 6.3 of the party vote last election and New Zealand First 7.2 per cent.
He admitted that the coat-tailing rule was advantageous to Act because it held the Epsom seat and had a reasonable chance of holding it.

"That's the naked politics of it."

While it was in his own party's interest, he believed electoral systems should be changed infrequently so that voters had a predictable voting environment.

"I very strongly believe, even though I obviously have self-interest, that to use a majority in Parliament to increase their own chance of winning the next election is absolutely terrifying from a democratic point of view.

"That's the kind of thing that will create riots and protest in the street."

Seymour also defended the one-seat rule saying the designers of MMP were trying to achieve a tradeoff between proportionality and "keeping the nutters out."

"They said either you get 5 five of the whole [voting] population or you get about 40 per cent of a particular area and if you can meet one of those tests, you need not meet the other one."