The National Party is calling for Prime Minister Helen Clark to front up to a parliamentary inquiry into a donation made to the New Zealand First leader Winston Peters' legal fund.
The Privileges Committee is considering whether Mr Peters should have declared a $100,000 donation from expat businessman Owen Glenn towards the cost of an electoral petition in Tauranga after the 2005 election. Mr Peters claimed that National Party MP Bob Clarkson had overspent on his successful campaign.
Miss Clark revealed last Thursday that Mr Glenn told her in February Mr Peters had approached him for money. She says Mr Glenn told her about the payment when the two met at the opening of Auckland University's business school.
National leader John Key says Miss Clark has kept the public in the dark for six months and is now closely linked to the scandal around Mr Peters. He says she should appear before the Privileges Committee to give her version of events.
However, Miss Clark says she will cross that bridge if it comes to it. The Prime Minister says the Privileges Committee hearing is about whether the donation is a gift, and she says she cannot shed any light on that.
On Monday, Labour Party president Mike Williams said he was happy to appear before the committee, but again repeated he did not suggest Mr Glenn as a potential donor.
Mr Williams says he talked to Mr Peters' lawyer Brian Henry about the electoral petition in Tauranga, but at no time suggested he should approach Mr Glenn for money.
ACT Party leader Rodney Hide says Mr Williams and Miss Clark should give evidence to the committee.
The Serious Fraud Office announced last Thursday it is investigating donations to New Zealand First by businessman Sir Robert Jones and the racing industry's Vela family.
A lawyer for Mr Peters said on Saturday the matter could be wrapped up quickly.
However, Mr Hide expects the investigation will take months and will hang over the election. He says the nature of the complaint means it will take more than five minutes to resolve.
Mr Peters stood down as Foreign Affairs Minister on Friday. His portfolios are being handled by Miss Clark.