Labour Party leader David Cunliffe has been embarrassed by revelations that he wrote to the Immigration Service in 2003 on behalf of businessman Donghua Liu.
The revelation comes a day after Mr Cunliffe said he had never met the Auckland property developer or advocated on his behalf. Deputy Prime Minister Bill English says Mr Cunliffe's credibility is in tatters.
David Cunliffe still stands by his answer and on Wednesday told reporters that it was based on the fact his electorate office had checked whether he had had any involvement with Liu and said he did not.
"I gave an honest answer as I recalled it and as my staff recalled it and there is nothing that I or my staff have done that is in anyway untoward or incorrect."
Mr Cunliffe said the letter also makes it clear that he did not advocate on Liu's behalf, but simply asked if the businessman could be told how long his application would take. He said he has no recollection of ever meeting Liu, despite signing the letter.
He told Radio New Zealand's Checkpoint programme he rejects the assertion from National that this reflects badly on his trustworthiness and believed the controversy would pass in a few days.
"The public's wise enough to know that this close to an election the fact that this has surfaced at all is politics as usual by the Government and they're throwing a bit of mud. They know that I'm a hard-working MP. I've had over 10,000 inquiries in cases in my office since 2001."
Mr Cunliffe said to his knowledge, there are no other undeclared donations or other matters that could cause him embarrassment. The general election will be held on 20 September.
Credibility in bits, says English
But the problem for the Labour Party leader is that he has repeatedly attacked the National Party over its links to Liu, who is due to be sentenced on domestic violence charges in August.
Maurice Williamson was forced to resign as a minister in May this year after it was revealed that he had rung police about the charges Liu faced. As well, the businessman made a substantial donation to National, which prompted accusations of cronynism from Labour.
So Wednesday's revelation prompted Deputy Prime Minister Bill English to turn the tables on Mr Cunliffe and attack his character.
"These revelations are a real surprise, because there's been a couple of months of discussion about Liu and his donations. But it shows that you can't believe anything David Cunliffe says - especially if it's about money and the Labour Party."
Mr English says Mr Cunliffe's credibility has already been under question over the use of a trust to raise money for his Labour Party leadership campaign. "This really blows his credibility to bits."
Green Party co-leader Russel Norman does not want to get embroiled in the controversy.
Dr Norman said the controversy around Donghua Liu is one which affects National and Labour, but not the Greens. Nor would he comment on National's attacks on Mr Cunliffe.
"I wouldn't comment on whether he's being tricky ... Obviously, I'm just focused on the big issues for the country," he said.
Cunliffe confident of caucus support
David Cunliffe on Wednesday scotched suggestions that his leadership is under threat as a result of the revelation he wrote a letter on behalf of Liu.
"I have talked to a few of my senior colleagues in light of media speculation and I can assure you I have the confidence of my caucus."
He said to his knowledge, there are no other undeclared donations or other matters that could cause him embarrassment.
Mr Cunliffe will be frustrated, though, that his leadership continues to be dogged by mistakes. From holding the high moral ground on Donghua Liu's links to National, Mr Cunliffe has now been forced to defend his own conduct.
No comment from Liu
Radio New Zealand visited several Auckland properties associated with Donghua Liu seeking comment from him on Wednesday.
The addresses are linked to businesses he owns and two are located in the suburb of Remuera. One is worth $3.45 million, according to the Auckland Council's rates and property search.
When Radio New Zealand visited, builders were working on the home and said Mr Liu was not there. Another property around the corner was being rented out.
Liu's lawyer Todd Simmonds told Radio New Zealand that his client would not be commenting on any interaction between the businessman and David Cunliffe.