New Zealand’s Labour government has been rocked after Jacinda Ardern announced her shock resignation as prime minister, triggering a quick rebuild of its leadership team 10 months out from an election that opinion polls show it is on track to lose.

Declaring on Thursday she no longer had “enough in the tank” to continue in the top job, Ms Ardern shut the door on a career where her age, gender and charisma had made her a global star of progressive politics for more than five years.