A retired High Court judge who donated $115,000 to Labour says the party's principles reflect those of his religion.
In Labour's first large donation for some time, Robert Smellie, QC, gave $100,000 this month, on top of the $15,000 he gave in December.
Smellie told the Herald one reason was his religion.
"[Former PM] Michael Joseph Savage once said, 'Labour is Christianity in action'. And I am a practising Anglican and as such I see socialism as being far closer to the Gospel than free enterprise."
Returns of donations that exceed $30,000 are published by the Electoral Commission. Smellie told the Herald that as a judge he wouldn't have wanted his political persuasions to be known.
"That tends to make people think they are not going to be judged fairly. But I'm now within a year of 20 years since I was a judge on the High Court. I'm 86, soon to be 87, and this might be the last election that I see. It may not be, but it could be.
"So I really didn't see there was any difficulty about anybody who was interested in knowing that I had supported the Labour Party."
Smellie, who is not and has never been a Labour Party member, said he believed Labour had the best chance for many years to put itself in a position to form a Government.
But that would likely depend on "which way Winston Peters decides to jump" after September's election.
Even if Labour lost the election the donation would help them highlight the Government's failings, Smellie said.
"All that should be brought before the public. And if the Labour Party is strapped for cash, it just can't do it."
Labour Party president Nigel Haworth, who spends three or four days a week working on fundraising, has said Smellie's donation was "extraordinarily generous" and the party was "humbled and delighted".
Leader Andrew Little said the party had raised considerably more than at the same point before the 2011 and 2014 elections.
National's coffers received a big boost this month, when Inner Mongolia Rider Horse Industry donated $150,000. The company has sent 1200 New Zealand racehorses to China to race and breed, including New Zealand horse of the year and derby winner Mongolian Khan.
Its Chinese billionaire founder Lang Lin made his fortune in fast food and is known as Mr Wolf because he keeps the animals as pets.