WELLINGTON, New Zealand — The leader of New Zealand’s opposition National Party quit Tuesday morning just over two months from a general election and 53 days after he took charge of the right-of-centre party that is seeing its support stagnate.

The statement Todd Muller released at 7:30 a.m. said he was stepping down “effective immediately” and reportedly shocked his fellow lawmakers. They announced deputy Nikki Kaye would be the acting leader, while a full meeting of the party caucus was due to take place later Tuesday at which a new leader may be chosen but there are few obvious candidates.

“It has become clear to me that I am not the best person to be leader of the Opposition and Leader of the New Zealand National Party at this critical time for New Zealand,” Muller said. “It is more important than ever that the New Zealand National Party has a leader who is comfortable in the role.

“The role has taken a heavy toll on me personally, and on my family, and this has become untenable from a health perspective.”

The National Party has been embroiled for the past week in a scandal after it was revealed a junior lawmaker leaked private health details of New Zealand COVID-19 patients to news media. The information was provided by a former party president who received it confidentially in her capacity as acting chief executive of the Auckland rescue helicopter organization.

Muller has been widely criticized for his handling of the scandal and the veracity of some of his statements had been challenged. He was facing questions over when he knew the source of the leak and if he knew one of his most senior MPs had also received the information.

The private information was sent to three media organizations but was not published.

Muller was a low-profile member of the party when he was chosen to lead the coup that toppled former leader Simon Bridges, whose lack of popularity with voters had begun to worry MPs as the election approached.

National has struggled to dent the popularity of Prime Minister Jacinda Ardern, whose government has high approval ratings for its handling of the coronavirus pandemic. New Zealand has gone 73 days without a case of community transmission and has suffered a low toll of 22 deaths.

Life has returned to mostly normal with schools, bars and restaurants all open and with packed stadiums at sports events. Only international travel remains restricted, and New Zealand's only active virus cases are among returned travellers in quarantine.

The Associated Press