Labour hardman Trevor Mallard yesterday threatened to reveal secrets about the private lives of National MPs if they keep calling him and his colleagues corrupt in the election spending battle.
National Party deputy leader Gerry Brownlee hit back by calling Mr Mallard a guttersnipe, saying that if he acted on his threat, National would reciprocate.
This would end what is known in politics as the "nuclear deterrent" - not dishing dirt on opponents so they don't dish it on you.
Mr Mallard would not confirm that his threatened revelations concerned sexual liaisons or say who he would target.
"Clearly members on our side know things about National Party members that I would describe as hypocritical behaviour," he said.
Asked if he was squeaky clean himself, he said: "I'm never going to claim I'm as pure as the driven snow in all things, but one thing is absolutely clear and that is I have integrity and I am not a hypocrite."
He'd had "an absolute gutsful" of having had his integrity impugned by being called corrupt.
"My reaction is much more a personal reaction than a political one."
It is almost certain that Prime Minister Helen Clark condoned Mr Mallard's tactics.
He told Parliament there were generally areas that were "off limits", but when aspersions were cast on MPs' integrity, the rules did not apply.
"If members opposite, or National Party members outside tell lies about us, we will tell the truth about them."
He then told National MP Nick Smith, who was interjecting, to "think very carefully about the husband that he has threatened recently" - a claim Dr Smith denied.
Mr Brownlee then said: "Mr Mallard needs to know that if he persists along this line, if he refuses to back off, refuses to apologise, then subsequent speakers may cause him quite a problem. I'm sick of it."
Mr Mallard: "It may well just be that we are getting close."
Mr Mallard's threat was made in the general debate after yet another tumultuous question time over the election spending issue.
The political storm started last month after a draft finding from that the Auditor-General that most parties had made illegal use of taxpayers' money for election advertising.
Among expenses cited was Labour's $446,000 pledge card.
Labour this week decided to mount its own campaign over the Exclusive Brethren's $1.2 million anti-Government campaign in last year's election, and accuses National of getting secret donations from big business in exchange for policies.
Helen Clark yesterday said she wanted all political donations of more than $250 to be declared and the donors named.
This is a move to attack National's reliance on anonymous donations channelled through trusts.
National claimed Helen Clark had declined to attend a meeting with the Auditor-General about another draft report before last year's election because her plans to spend money on the pledge card had been "locked in".
She said Mr Mallard was her representative at the meeting.
Mr Brownlee countered Labour's allegations of "cash for policy" by linking Labour donors and policy.
"The unions to focus on employment law, from Toll New Zealand to give it cheap access to the rail track and a cash deal for its business, from Westpac Trust to get the Government's banking business."
Mr Mallard said he had seen such intensity of feeling between the parties in Parliament only a couple of times since he was first elected in 1984.
- Additional reporting Paula Oliver