The Police Association says a frozen budget is starting to have a serious impact on policing.
The association launched its election wish-list in Wellington yesterday which included tougher penalties for fleeing drivers and a blanket ban on gang patches.
The police's budget has been frozen since 2010 and currently sits at $1.46 billion for core spending.
In that time, the crime rate has dropped to a 29-year low with just over 360,000 offences recorded last year.
But Police Association president Greg O'Connor said police resources were now stretched too thin.
"Police have been expected to do a lot more work to absorb a lot more. There is a fine line between becoming more efficient and actually being inefficient because of a lack of resource," he said.
"Our fear is that we've crossed that line."
He is worried the police could return to the late 1990's when lack of resourcing led to scandals such as police cars being unwarrantable and child abuse files going un-noticed.
Mr O'Connor said without more investment those sorts of mistakes will start to creep in.
"What was flexibility very quickly crosses the line and becomes plugging gaps. At the moment we are starting to plug gaps," he said.
But Police Minister Anne Tolley said that was rubbish.
"That's certainly not the advice I get from the Commissioner and the Deputy Commissioners," she said.
She said she has to rely on the advice they give her.
Ms Tolley said the association hadn't adjusted to a recent restructure of the police.
"When they start talking about having so many police per head of population I think that's very old style public service. We are focussed on getting results for our community."
Ms Tolley said there were no guarantees the police would get more funding in a National-led government.
Labour's Police spokesperson Jacinda Adern said it was clear more funding was needed urgently.
"They at the moment simply do not have enough resource to do the job. We would put an end to the frozen and decreasing budgets," she said.