[comment caption=Do you think Labour's policies have had any effect on crime rates?]When fortune turns against a government, it often turns with a vengeance.
That is happening to Labour. With the election campaign only weeks away, Labour already had enough on its plate without the killing of Manurewa bottle-store owner Navtej Singh.
The economy is heading into recession. The only question is how deeply - and how hard it starts to bite before election day.
That Finance Minister Michael Cullen felt impelled to warn in advance to soften the impact of pending poor GDP figures spoke much for Labour's worry.
Now, for the second time in six months, Labour has been confronted with a spate of murders which have again induced near-hysteria over law and order policy in some quarters and conveniently allowed National to come out and box Labour around the ears.
The sheer callousness of the killing of Mr Singh makes it a political nightmare for Labour.
The party can justifiably defend its record, both in strengthening policing and lengthening prison sentences for serious offences. But no matter what Labour has done, this case will persuade many it has not been enough.
Despite the standard promises from political parties to safeguard personal security - and Labour's manifesto is no different - people are realistic about the State's capacity to do that all the time.
What strikes terror into the wider community - and why the killing of Mr Singh has provoked such a reaction - is how some members of the "underclass" can value someone's life so cheaply.
While everyone skirts the issue, there is the not-so-small matter of race when an Indian shop-owner is gunned down and the subsequent row of young faces appearing in court are of Samoan extraction. This is very delicate territory for Labour.
The party relies on the party vote of Maori and Pacific islanders in seats like Manurewa where those two groups make up more than half the electorate's population.
At the last election, three South Auckland electorates alone accounted for more than 6% of Labour's total nationwide party vote. Labour's average party vote nationwide was around 13,500 per electorate. In Manurewa, Manukau East and Mangere, it ranged from around 18,000 to nearly 21,000.
Labour will have a hard enough job getting those voters to the ballot box this time without dumping on them over crime.
National is not so constrained. Labour privately accuses National of indulging in "dog-whistle politics" by making statements to induce "white fright" - not just among those Pakeha living in Manurewa, but among the wider Pakeha population.
With the constant screening of security camera footage of the robbery intensifying revulsion and consequent calls for retribution, the killing was always going to be thrust into the political domain.
Labour realised that and sought to front-foot its response, rather than look defensive.
But short of pandering to populism by promising "lock `em up and throw away the key"-type prison sentences, Labour knew it could not offer any instant remedies to appease the mix of fear and anger over the killing which was reinforced by two subsequent homicides in the locality.
Nor was it much use putting the deaths into context by arguing they were a coincidental cluster rather than an ominous trend.
The number of homicides nationwide has dropped from 109 to 88 in the past two years. There were just eight homicides in the Counties-Manukau police district last year compared with 27 in 2006.
Overall, on a population basis, recorded offences in Counties-Manukau have fallen since Labour took office. Violent offences have risen, but much of the increase is put down to greater reporting of domestic assaults.
But the facts cannot compete with emotions running so high over the death of a hard-working man who was trying to establish his business and build a future for his wife and three young children.
That was how John Key characterised Mr Singh, describing him as someone imbued with National Party principles.
That inclusion of Mr Singh as "one of us" was designed to suggest only National understands the daily risk of violence faced by shop-owners in the poorer suburbs of the country's cities.
This attempt to marginalise Labour as being indifferent to crime produced a predictable reaction with the governing party accusing Mr Key of shroud-waving and exploiting Mr Singh's death for political gain.
However, it would be naive to expect an opposition party to act any differently in election year, given any consensus not to exploit the murder would only be to Labour's benefit.
As for insensitivity, Mr Key argues the prime minister had been the first to bring the matter into the political domain by promising action on the profusion of liquor outlets which are seen as a major factor in increasing violence in poorer suburbs.
Nevertheless, Mr Key has been running a particularly hard line on the killing of Mr Singh - stronger than what might have been expected from Simon Power, National's law and order spokesman, who was in Australia this week and thus absent from Parliament.
Mr Key is more of a natural conservative on law and order than his centrist inclinations would suggest. But his political instincts also told him voters are in a punitive mood.
Labour argues National's plan to send young offenders to boot camps won't work; that they only teach young people how to take up a life of crime.
Labour also points out it is not clear that all those facing charges over Mr Singh's murder have previously come to the attention of the police. In other words, they would not have gone to boot camp even if ones already existed.
The public don't care about such complications. They just think young criminals could benefit from some enforced discipline.
Lacking the boot-camp option, Labour has tried to quell the furore by pointing to its tougher sentencing policy for major crimes, the success of which is evidenced by the consequent blow-out in prison inmate numbers.
It also stresses its countless initiatives for better policing and more effective programmes run by State social agencies in areas of social deprivation.
The prime minister has brought the heads of government departments together to come up with new policies to help Manurewa's youth stay on the straight and narrow.
She has got her officials in the prime minister's department to speed up the review of liquor licensing policy, while local Labour MP George Hawkins has finally been able to get his related private member's Bill before Parliament.
The latter moves on liquor might be belated, but it is important for Labour that it be seen to be doing something.
In terms of cooling the debate over law and order provoked by Mr Singh's death, however, it is the political equivalent of fighting a raging bush-fire with a garden hose.
- John Armstrong is the New Zealand Herald's political correspondent.
