Labour Party leader Phil Goff says he needs to see evidence that arming police will make them and the community safer before supporting such a move.
Police Minister Judith Collins supports a call for firearms to be installed in every police car.
The Police Association wants to go further than Ms Collins' suggestion and have police officers themselves armed.
President Greg O'Connor says the fact nine officers were shot in two years - two fatally - is evidence enough that police should carry guns.
But Mr Goff says he wants to see overseas evidence that fewer police per capita are shot when they are armed.
Tougher line on drivers fleeing from police
Mr Goff also told a conference of the association in Wellington on Friday that Labour is proposing tougher punishments for drivers who flee from police, including the possibility of imprisonment for a first offence.
Seventeen people have died this year in connection with police chases.
Mr Goff says officers are damned if they do pursue vehicles and also damned if they don't.
He says immediate impoundment and confiscation of cars is an option, as is imprisonment, including for a first offence.
Mr Goff says Labour is considering how to minimize paperwork and related procedures so they can spend more time on the beat.
One measure under consideration may be to use breathalyser evidence alone to charge someone with drink-driving so officers don't get tied up with collecting blood tests.