As election looms, New Zealand politics has been turned on its head by surging popularity of Labour leader Jacinda Arden

Three weeks before a general election, the dramatic rise of New Zealand opposition leader Jacinda Ardern was highlighted by an opinion poll that put her Labour Party ahead of the ruling conservatives for the first time in more than a decade.

The unexpected result late on Thursday caused the New Zealand dollar to drop before regaining some ground as traders priced in an uncertain election outcome.

Commissioned by Television New Zealand, the poll indicated Ardern’s Labour Party is favoured by 43 per cent of voters, compared to 41 per cent who favour the incumbent National Party, led by Prime Minister Bill English.

That result seemed unthinkable a month ago. A similar poll taken just before the previous leader quit and Ardern took the reins showed the Labour Party on 24 per cent support and the National Party on 47 per cent. Most commentators at the time were predicting National would easily win the election.

Some New Zealanders are describing the new mood as “Jacinda-mania” and the 37-year-old’s rapid ascent as similar to that achieved by other young, charismatic leaders such as President Emmanuel Macron in France and Prime Minister Justin Trudeau in Canada.

Yet National retains strong support and it remains unclear which party will be in a position to govern after the election. That’s because large parties typically must form alliances with smaller parties under the nation’s proportional voting system. And one key small party, New Zealand First, has yet to say which of the larger parties it will back.

The poll result came ahead of the first televised debate between Ardern and English. The leaders were polite with each other as they tussled over taxes, housing and immigration. Both appeared to perform relatively well and neither made any obvious gaffes.

One of Ardern’s stronger moments came in response to a viewer question. A cancer patient asked if either candidate would consider legalising medical marijuana. Told by moderator Mike Hosking she had 30 seconds to respond, Ardern said: “I don’t need 30 seconds, Mike. The answer is absolutely yes.”

English performed well when discussing the nation’s relatively strong economy, which he has helped guide over the past nine years. He said Ardern wanted to increase taxes while he would reduce them. “We can achieve our social and environmental objectives at the same time as have a strong economy, not at the expense of it,” he said.