What role did Winston Peters and New Zealand First play in Jacinda Ardern becoming prime minister?

Following the 2017 general election in New Zealand, the New Zealand First party held the decisive "kingmaker" role because neither the incumbent National Party nor the Labour Party had secured enough seats to form a majority government on their own.123

Winston Peters, the leader of New Zealand First, spent weeks negotiating with both parties. On October 19, 2017, Peters announced that his party would enter into a coalition government with the Labour Party, which would also receive "supply and confidence" support from the Green Party. This partnership provided the necessary parliamentary support for Jacinda Ardern to become the 40th prime minister of New Zealand.12