WELLINGTON — New Zealand’s conservative Prime Minister Bill English conceded on Monday he was "worried" about next month’s general election, as support for the opposition continued to surge.

The centre-left Labour Party has enjoyed a huge boost in support ahead of the September 23 election after gambling on a charismatic new leader in 37-year-old Jacinda Ardern.

In a phenomenon local media have dubbed "Jacinda-mania", Labour’s support has rocketed since she took over earlier this month, making a change of government a realistic possibility.

Labour’s support has risen about 14 per cent to 37 per cent, just three points behind English’s National Party, according to internal party polling leaked to media over the weekend.

A separate TVNZ poll late last week had Ardern and English level pegging with 30 per cent support as preferred prime minister, a rise of 24 percentage points for the Labour leader.

The figures mean there is no guarantee National will retain office under New Zealand’s complicated proportional voting system, which means major players invariably have to form alliances with minor parties.

"We’re worried in the sense that we’ve got to lift our support in order to be able to form a sensible government after this election," English told Radio New Zealand.

He accused Labour of concentrating more on personality politics than articulating a comprehensive campaign platform.

"They might be talking about the person but we don’t come across anyone talking about Labour Party policies," he added.

English took over the New Zealand leadership late last year after the shock resignation of the popular John Key.

While he is yet to replicate Key’s personal appeal to voters, English has staked National’s hopes of a record-equalling fourth term on maintaining the same policies as his predecessor.

"New Zealand’s doing pretty well. We can build on that success," he said.

Meanwhile, English suffered a blow when one of his government’s coalition partners, Peter Dunne of the United Future Party, announced he would not contest the election.

Dunne supported National for three terms, serving as a minister in the government, but recent polling showed him trailing Labour’s candidate in his Wellington electorate of Ohariu. — AFP