If there is a single anxiety underlying the restive mood of many voters in western democracies at present it is undoubtedly immigration, for which those voters blame high house prices and a housing shortage, low incomes, unemployment, crime and sometimes terrorism.
In all likelihood their mood has less to do with all of these problems than with the fear that their nation's ethnicity, character and culture are being undermined, but that is a view few dare to express in public because they will sound racially prejudiced.
They feel gagged by political correctness, which adds frustration and anger to their fear.
So the immigration debate proceeds on the safer territory of housing, incomes and jobs.
All are genuine problems associated with population growth, and deserve debate.
It is, however, a "problem" we are fortunate to have.
It is certainly preferable to the alternative. This country's population barely grew during the last quarter of the 20th century. Most years more New Zealanders left than arrived, and as recently as 10 years ago we were still worrying about the exodus of our young.
Today the population is rising again. More young Kiwis are returning, fewer are leaving and migrants are coming to study, work and, in some cases, to stay.
The number who arrived last year intending to stay a year or more exceeded those leaving for a year or more by 71,300, slightly exceeding the record set the previous year.
Many of them are students recruited by our schools and universities "exporting" education. Their fees add to the institution's income and improves its facilities for all.
Some are here only nominally for study and really to work, too often for sponsors who are in a position to exploit them. That is a problem the Herald exposed last year and it demands vigilant enforcement of New Zealand's employment laws.
Others are here purely for working holidays and bring skills highly valued by industries such as tourism and hospitality. Both these categories of migrants are accused of taking jobs our young unemployed could do.
Prime Minister Bill English met that suggestion this week with the observation employers in sectors such as horticulture and hospitality complain they have vacancies they cannot fill.
It stands to reason employers would prefer a stable staff of New Zealanders to migrant labour if their aptitude and skills were the same. But the Prime Minister says a lot of our young people cannot even pass a drug test.
Be that as it may - it does seem an exaggerated claim - we have an astonishing number of young people, more than 70,000 now, who are not in employment, education or training.
The Labour Party leader says the Government is not doing enough to help them but considering the abundance of tertiary and workforce training courses provided around the country these days, it is not clear what else Andrew Little proposes to do.
It is clear, though, the immigration and its proxy issues of housing and employment are going to be the heated topics of this year's election campaign.
It will be hard for the Government to win a proxy war if the voters' real fear of ethic diversity is left to fester unchallenged.