Jacinda Ardern has long excelled in seeming like a normal person. She has incredibly strong political instincts, which she managed to translate into big-screen empathy and humour. This was evident as she took the reins of the New Zealand Labour party in 2017, after it had worked through four men who screamed “politician” as soon as they walked into a room. Ardern was a breath of fresh air. She soon took Labour to victory and managed to keep that “not quite a politician” vibe afloat through two historic terms and many incredibly political moments, as New Zealand faced its worst ever terror attack and the pandemic. Her shock decision to quit just confirms this image. What normal person hasn’t taken a summer holiday and not wanted to return to work? Who exactly would pick a year of 18-hour work days fighting an election they would probably lose over the peace of civilian life, where you have a child about to start school and a fiance you keep putting off marrying? But while her exit is understandable on a human level, it is confounding on a political one. Labour MPs and supporters have every right to be furious. Ardern was facing a very steep hill at the October election, which explains more than any other reason her decision to leave. Inflation, high interest rates, and a likely recession would make that the case for any incumbent government, and her government has also made a litany of unforced errors in recent months. Yet she remained ahead on the preferred prime minister polls, and remained Labour’s best weapon against an opposition leader the public have not quite warmed to. According to data from the New Zealand Election Study, the huge number of voters who switched from National to Labour between 2017 and 2020 had overwhelmingly strong feelings of adoration for Ardern. These swing voters decide elections, and while some of them may have changed their mind, anyone who liked a leader this much remains persuadable. She leaves the party in far worse shape to fight this election than it would have been under her leadership. Worse, her decision appears to have genuinely surprised the party, meaning succession-planning has not been thought through. Her deputy, Grant Robertson, the only figure in the party with anything approaching her stature with the public, has already ruled himself out, all those rumours about the pair having made Gordon Brown-Tony Blair style deal now scotched. Her legacy will be for historians to figure out. Some will see her as Labour’s greatest postwar leader – a strong leader through massive crises who also gave the party its largest win in decades. Others will compare her unfavourably with someone like Helen Clark – a soldier for the party who stuck around through two losing election campaigns and three winning ones, remaking New Zealand significantly in her nine-year term of power. Ardern has lost the chance to really embed her vision of social democracy into the country with another win. If Ardern had lost and decided to leave after the election, the party could have had the time and space of opposition to pick someone fresh and interesting from recent intakes. But they now need a new prime minister, someone who can wrangle with the teeming mass of bureaucracy and lead the country on day one. That probably leaves the party with a figure such as Chris Hipkins, a strong minister, but not one who will draw some kind of huge contrast with the opposition leader, Christopher Luxon. Even if the party was doomed to defeat either way, there is a difference between a close loss and a big one, a difference you can measure in fresh new faces to revitalise your party, and the parliamentary funding desperately needed for research staff. Ardern’s exit will come as a shock to many international fans, who saw her as a beacon of progressive hope during the Trump years. But it proves a lesson this same movement should have taken from Barack Obama, or indeed Bernie Sanders: investing an actual person with this much political importance is always dangerous. If your plan to win an election hinges so strongly on an individual, you always run the risk of them leaving the field.