A month ago, just 24 per cent of New Zealanders supported the country's Labour Party.

Now the latest opinion poll shows that number has jumped to 43 per cent — the highest it's been in more than 10 years.

And its almost all thanks to Jacinda Ardern and what local media are calling 'Jacindamania'.

Who is Jacinda Ardern?

Ms Ardern is the new leader of New Zealand's Labour Party, and the country's new Opposition Leader.

She took over from former Labour leader, Andrew Little, just one month ago during some pretty dire poll figures.

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At 37, she's the party's youngest ever leader and has been compared to the likes of France's Emmanuel Macron and Canada's Justin Trudeau.

She's also the MP for the Auckland electorate of Mount Albert.

Why is she so popular?

Because she's mastered the art of the selfie? ( Twitter: Jacinda Ardern )

According to Barry Soper, the political editor for New Zealand's Newstalk ZB radio network, it's because she's a great communicator.

"What she has done, she has been able to communicate," he told The World Today.

"She's very good at articulating, and that's got her where she is at the moment."

But he said the country's apparent desire for change was also boosting her popularity ahead of the election.

"She's struck a note obviously with the general public … so it's sort of this sweeping mood for change," he said.

What does she stand for?

Ms Ardern has made her views on immigration, housing and the economy well known. ( AP: Mark Baker )

During the first televised leaders' debate, Ms Ardern had some particularly strong things to say about housing and medical marijuana.

On housing, she said she wanted to make sure her generation could get into the market.

(ICYMI: New Zealand is at the moment suffering from a skilled labour shortage and is struggling to build enough houses to meet growing demand).

But on medical marijuana she was even stronger.

Given 30 seconds to respond to a cancer patient's question of whether she would consider legalising the treatment, she said this:

"I don't need 30 seconds … the answer is absolutely yes."

What challenges does she face?

While Ms Ardern has managed to take Labour to an unlikely two-point opinion poll lead, she still faces some heavy challenges.

Firstly, Prime Minister Bill English and the National Party have retained strong support ahead of the election.

Prime Minister Bill English is still very popular in New Zealand. ( AAP: Lukas Coch )

The party has been in power since 2008 and has been credited with helping grow a relatively strong economy for the country.

Soper said not even Ms Arden could deny that in the leaders' debate.

"[Mr English] even had [her] at one stage saying that she would inherit a robust and successful economy," he said.

Secondly, Ms Ardern is also the newbie.

"She's relatively inexperienced. I mean, she only became deputy leader of the Labour Party in February this year," Soper said.

And already she's faced questions about being a young woman in politics.

In fact she'd only been in the top job for less than 24 hours when she was first asked by TV host Jesse Mulligan on The Project about how she would balance her career and potential motherhood.

"A lot of women in New Zealand feel like they have to make a choice between having babies and having a career, or continuing their career at a certain point in their lives — late 30s," he said.

"Is that a decision that you feel you have to make, or that you feel that you've already made?"

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Then just a few weeks later a minority party leader posted on Twitter that Ms Ardern needed to prove she was not "lipstick on a pig".

That prompted sharp criticism on social media, where many New Zealander women posted photos of themselves with tubes of lip gloss to call out what they said was misogyny.

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And we also can't forget her diplomatic stoush with Australia.

In August, Foreign Affairs Minister Julie Bishop accused Ms Ardern's party of undermining the Australian Government after it was revealed that enquiries had been made about Deputy Prime Minister Barnaby Joyce's citizenship.

Ms Ardern described Ms Bishop's comments as "false claims" and invited Ms Bishop to call her to "clarify matters".

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The election will take place on September 23.

ABC/wires