How did the New Zealand Labour Party form a government after the 2017 election?

Following the 2017 general election, the New Zealand Labour Party did not secure an outright majority, despite the New Zealand National Party winning the most seats. Both major parties engaged in weeks of negotiations to secure the support necessary to form a government.12

Ultimately, Jacinda Ardern—who had become the Labour leader in August 2017—successfully formed a coalition government with the New Zealand First party. Additionally, the new government operated with "confidence and supply" support from the Green Party. This arrangement brought an end to nearly a decade of National Party rule and saw Ardern become the youngest prime minister of New Zealand in approximately 150 years.341