Immigration is a hot topic coming up to the election but just talking about it can be a tense experience. Noelle McCarthy asks what those tensions are, who is stoking them and why are we so touchy about it all?

Are we shouting past each other on immigration? In the second episode of Slice of Heaven, Noelle McCarthy talks to Winston Peters, Jim Bolger and others - and John Daniell and Paul Spoonley explain the link between New Zealand First's polling and immigration levels.

Recent political results in the US and in Europe remind us that immigration remains a sensitive issue that generates anxiety and anger among some.

New Zealand has been here before. It was a galvanizing topic in the 1996 general election that translated into substantial support for a new political party, New Zealand First.

Will it have the same effect in 2017?

"It is axiomatic that immigration is about ethnicity" - New Zealand First leader Winston Peters, Slice of Heaven, Ep 2

One of the ironies is that New Zealand First appears to need high immigration numbers to generate support. And in 2017, they certainly have that with the net immigration rate hovering around 72,000, an historic high.

This association between immigration flows and support for New Zealand First is obvious in this graph of net migration and the seats won by the party over the last two decades.

The correlation is broken only in 2008, the year New Zealand First's political donations were investigated by the Serious Fraud Office. Although the SFO found no basis for fraud charges to be laid, the party's leader, Winston Peters, lost the Tauranga electorate and the party fell below the 5 percent threshold, meaning they would have no seats in Parliament. Since then support has again risen as the number of immigrants has increased.

If the correlation holds, it suggests the potential for a strong New Zealand First surge this year.

This growing anxiety about immigrant numbers has been confirmed by recent polls, notably UMR earlier this year. The electorate is divided - although not as much as some would have us believe.

The Ministry of Business, Innovation and Employment polling in 2016, the annual Asia New Zealand Foundation polling and the Ipsos Public Affairs survey in 2016 all show that the support for immigrants and immigration is relatively positive - much more so than most other countries.

A group gathers to celebrate Africa Day in Wellington earlier this year

But there is also concern that immigrants are not adapting to New Zealand and some see a country and its values under threat…

Go to this episode on rnz.co.nz for more details