Labour has lifted by six points to its highest level since March 2014 in the Roy Morgan Poll.
Labour is up to 32 per cent in the poll - up six points from a fortnight ago while National was down six points to 43 per cent support.
However, the impact of Labour's analysis of leaked Auckland real estate data remains unclear.
The poll of 886 voters began on June 29 and ended the day after Labour released that data on July 11.
The data has proved controversial among some Labour supporters because it was based on Chinese surnames.
The Green Party were steady on 13 per cent.
It is the first time since May 2014 that Labour and the Greens together have had more support than National.
The poll also showed confidence had dropped to its lowest level since September 2013 - 51 per cent of voters said the country was heading in the right direction, down from 62.5 in Roy Morgan's post-Budget June poll.
Roy Morgan executive chairman Gary Morgan put that down to the economic uncertainty from Greece and China, the drop in the dollar and low dairy prices.
The Roy Morgan poll can be bouncy. In March Labour was at 31 but had dropped to between 25 and 27 per cent since then while National had bounced from 45 per cent to 54 per cent in May, just before the Budget.
Little under fire
The numbers will be a boost for leader Andrew Little. He has come under fire from his own ranks for singling out Chinese people in the debate.
The Herald revealed today that former Maori members' chairman Shane Te Pou has written to the party demanding his personal data be removed from Labour's database of home buyers, which it claims is the same information leaked from Barfoot & Thompson.
Te Pou cited the Privacy Act in the letter after being told by the estate agency that the purchase of his family's house was likely among those used to bolster statistics purporting to show people in China were buying up New Zealand houses.
In revealing the statistics, Labour's housing spokesman Phil Twyford tweeted: "People of Chinese descent bought 39.5% of houses sold by major (Auckland) real estate firm. This is foreign money."
Te Pou is married to Annie Du, who is of Chinese ethnicity. He told the Herald his wife's name was used to buy the family home during the period covered by Barfoot & Thompson sales data, obtained by Labour.
Te Pou wrote: "I am Maori. My wife is of Chinese descent. My money is not foreign."
His letter to the Labour Party - addressed to leader Andrew Little - cited a section of the Privacy Act which banned the collection of information which would intrude unfairly or unreasonably on individuals.
He said the information had been released from Barfoot & Thompson through a staff member to the Labour Party in a way which was "certainly unlawful". "The use of it to describe Maori New Zealanders as Chinese, 'foreign money', and the cause of a housing problem is certainly unfair."
He wrote to Little telling him one of his children asked: "Daddy, why are people angry at Chinese."
"This demonstrates that actual harm has been caused to our family."
The letter to Little was the first step in seeking redress and was the first step in making a formal complaint to the Privacy Commission.
Te Pou told the Herald Labour was guilty of "racial profiling".
He said the issue of foreign ownership was important and needed to be discussed - but Labour had gone about it in the wrong way.
"It's a conversation we should have had without talking about a particular ethnic group."
He said the decision to isolate and highlight Chinese people went against Labour's core principles.
"They got a lot of Chinese sounding names and basically came up with an equation that I think is not robust but more importantly amounted to racial profiling."
He said he believed Little and Twyford were "decent human beings". "What they have done in this case is just wrong."
Te Pou said he would lay a formal complaint with the Privacy Commission and Human Rights Commission should the party not address his concerns.