The centre-right National Party, led by Prime Minister Bill English, had governed since 2008 in a minority government. It was the first election for English as incumbent Prime Minister, having replaced John Key on 12 December 2016 and the first since 1975 where both major parties had leadership changes. The main opposition parties to the National government were Labour (the official opposition), led by Jacinda Ardern, the Green Party, and New Zealand First.