An emotional Trevor Mallard has apologised publicly for punching a National MP.
Comments in parliament about the cabinet minister's love-life resulted in a brawl outside the parliamentary debating chamber between Mallard and Tau Henare.
The cabinet minister, says he deeply regrets his behaviour, and accepts his political future, could be damaged by it.
Mallard says what he did was "absolutely wrong".
"It's one of the most stupid things I've ever done in my life and I really regret it."
The trouble started when Henare goaded Mallard, who has recently separated from his wife, over his personal life.
Mallard then suggested they continue the discussion in the lobbies.
There was a heated argument and it is understood Mallard then struck Henare and the pair had to be prised apart.
Henare says there was "a bit of an altercation".
"I got tapped and Mallard has apologised profusely. I've accepted his apology and as far as I'm concerned that's the end of the matter," he says.
Henare wouldn't say what he said to Mallard to provoke the reaction.
"What I said in the House, stays in the House," says Henare.
He also says he will not apologise for what he said.
"It is a robust environment...if everybody was to apologise every five minutes for what they said in there (debating chamber), then this place wouldn't be a debating chamber," says Henare.
The scrap between the pair has been condemned by both their party leaders.
Prime Minister Helen Clark says that whatever the reason there was no excuse for violence.
"I've recently launched a campaign saying it's not okay to hit anyone, not okay to hit people in a family, it's not okay to hit anybody. That's why I say both men should be looking in the mirror."
Clark is about to reshuffle her cabinet and may have difficult giving Mallard social portfolios.
"I'm taking a lot of factors into account in the reshuffle that I'm planning but I don't have anything to say about that today," she says.
National Party leader John Key says he has expressed his disappointment to Henare that the incident happened and says there is no place for violence in politics.
"I've had a discussion with him this morning. I've said I find the whole event disappointing. It's just not a great look for the New Zealand parliament."