New Zealand Prime Minister Jacinda Ardern will step down by next month because she no longer has “enough in the tank” to do the job, she said.

“I’m leaving because with such a privileged role comes responsibility — to know when you’re the right person to lead and also when you are not,” said Ardern, who leads the country’s Labour Party and won her first term 5 1/2 years ago.

Ardern, 42, said Thursday afternoon local time (7 p.m. ET Wednesday) she would not seek reelection and planned to resign no later than Feb. 7.