WELLINGTON – New Zealand’s main opposition gambled on a leadership change just weeks before a general election on Tuesday after polling showed it was heading for disaster at the ballot box.

The centre-left Labour Party selected 37-year-old Jacinda Ardern to take it into the September 23 election, making her the youngest leader in its 101-year history.

The move came after outgoing leader Andrew Little quit in response to a string of opinion polls that put Labour’s support at 20-year lows of 23-24 per cent, giving it no chance of forming a government.

Ardern, who was Little’s deputy, becomes Labour’s fifth leader in four years as she seeks to prevent the centre-right National Party-led coalition winning a fourth term.

"This team is about to run the campaign of our lives," she said after winning the leadership unopposed.

Ardern was elected to parliament in 2008 after working as a political adviser and has long been seen as the face of a new generation coming through the Labour ranks.

With her new deputy Kelvin Davis standing alongside her, she promised "relentless positivity" and appealed to young, idealistic voters.

"We’ll be talking to a new generation of voters, but not just about their own personal circumstances," she told reporters.

"As a country, we can do better than this," she added.

Little, 52, admitted he had failed to get his message across during more than two years as leader.

"Recent poll results have been disappointing. As leader, I must take responsibility for these results," he said.

"I do take responsibility and believe that Labour must have an opportunity to perform better under new leadership through to the election."

Prime Minister Bill English said the change of leadership would not solve Labour’s problems.

"They’re in disarray, the basic problem isn’t really the leadership, it’s they just don’t have a positive view of what New Zealand can achieve," he told reporters.

English took over as leader of the National Party after John Key’s shock resignation late last year.

While he does not have the personal popularity of his predecessor, the party’s vote share has held steady at around 47 per cent under English’s leadership.

However, he warned the Nationals could not be complacent because New Zealand’s complicated proportional voting system usually results in minority governments reliant on smaller parties as coalition partners. – AFP