A fresh-faced Jacinda Ardern entered office three years ago promising "relentless positivity" -- and New Zealand's leader has needed it in abundance as a succession of catastrophes besieged the nation and tested her mettle.

In a hectic first term, Ardern has faced New Zealand's worst terror attack, a deadly volcanic eruption, the country's deepest recession in more than 30 years, and the shared global threat of the Covid-19 pandemic.

Along the way, she also had a baby and became the international standard-bearer for progressive politics in an era of right-wing populist strongmen.

Ardern had been in office barely 18 months when a white supremacist gunman opened fire in two Christchurch mosques during Friday prayers, killing 51 Muslim worshippers and wounding another 40 on March 15 last year.

Jacinda Ardern walks with Al Noor mosque Iman Gamal Fouda ahead of unveiling a plaque in memory of the victims killed in the 2019 shootings
Jacinda Ardern walks with Al Noor mosque Iman Gamal Fouda ahead of unveiling a plaque in memory of the victims killed in the 2019 shootings AFP / SANKA VIDANAGAMA

Her deft and compassionate response to the gunman's rampage of hate defined the charismatic centre-left leader's image around the world.

When she donned a headscarf and comforted victims' families after the shooting, it resonated globally. She would later describe it as a spontaneous gesture of respect to the Muslim community.

But she also won plaudits for decisive policy action, including swiftly enacted gun law reforms and a push to force social media giants to address online hate speech.

The New Zealand public used the October 17 general election to emphatically back the 40-year-old's performance, giving her a second three-year term in office.

Ardern's campaign pitch focused heavily on her government's success in containing the coronavirus, with New Zealand recording only 25 deaths in a population of five million people.

Ardern faced New Zealand's worst terror attack, a deadly volcanic eruption, the country's deepest recession in more than 30 years -- and Covid-19
Ardern faced New Zealand's worst terror attack, a deadly volcanic eruption, the country's deepest recession in more than 30 years -- and Covid-19 AFP / Marty MELVILLE

She argued that only her centre-left Labour Party could be trusted to keep New Zealanders safe with a combination of strict border controls and widespread Covid-19 testing.

"This has been a really tough time for New Zealand -- we've had a terrorist attack, a natural disaster and a global pandemic," she said.

"But in these tough times we've seen the best of us. We've been able to clear high hurdles and face huge challenges because of who we are, and because we had a plan."

Life within New Zealand has largely returned to normal after a strict lockdown earlier this year, barring a brief outbreak in Auckland that has now been contained.

With New Zealand's general election on the doorsteps, polls put prime minister Jacinda Ardern on track to win in what she dubbed the country's "Covid election". Here's a review of some remarkable moments of Ardern's three-year tenure
With New Zealand's general election on the doorsteps, polls put prime minister Jacinda Ardern on track to win in what she dubbed the country's "Covid election". Here's a review of some remarkable moments of Ardern's three-year tenure AFPTV / Marty MELVILLE

The success helped Ardern win a poll she dubbed the "Covid election" and the 55 percent personal approval rating she recorded in opinion polls ahead of the vote demonstrates the bond she has forged with fellow Kiwis in tough times.

Ardern grew up in the North Island hinterland, where her father was a police officer. She credits the poverty she saw there with shaping her beliefs.

She was raised as a Mormon but left the faith in her 20s due to its stance against homosexuality.

After completing a communications degree, Ardern began her political career in former prime minister Helen Clark's office before heading to Britain to work as a policy adviser in Tony Blair's government.

She was elected to parliament in 2008 and in March 2017 became Labour's deputy leader, saying at the time that she was not ambitious and saw herself as a backroom staffer.

Ardern transformed from self-described "policy nerd" to prime minister on a wave of "Jacinda-mania" after being thrust into the Labour leadership just seven weeks before the 2017 election.

She made headlines again a year later when she became only the second prime minister in the world to give birth while in office -- after Pakistan's Benazir Bhutto in 1990.

After Christchurch she again offered comfort to the nation, when the White Island (also known as Whakaari) volcano erupted last December, killing 21 people and leaving dozens more with horrific burns.

Ardern has constantly urged New Zealanders during the coronavirus crisis to "be kind", appealing for a unified approach from what she terms a "team of five million."

"We have to make the choice every single day to channel our own inner Jacindas," Winfrey said, advice many New Zealanders appear to have taken to heart in Saturday's election.