New Zealand's conservative opposition switched leaders Friday in a last-gasp bid to counter the record support Prime Minister Jacinda Ardern is enjoying for containing the coronavirus.

National Party lawmakers voted to ditch Simon Bridges after opinion polls predicted he was headed for a wipeout at a general election on September 19.

His replacement is former agri-business executive Todd Muller, who faces a mammoth task to make the Nationals competitive before Kiwis cast their ballots in less than four months.

Muller, 51, said his focus was on helping New Zealand's economy recover from the damage caused by the coronavirus epidemic.

"New Zealanders need a National government with the experience and management skills to get our country through the worst crisis since the end of the Second World War," he said in a statement.

Bridges, a former police prosecutor, has been accused in recent weeks of striking the wrong tone with the New Zealand public by attacking aspects of the Ardern government's coronavirus response.

His axing comes after two polls this week put support for his party at near 20-year lows.

New Zealand Prime Minister Jacinda Ardern is experiencing record high support
New Zealand Prime Minister Jacinda Ardern is experiencing record high support POOL / Mark Mitchell

Muller, who began his political career as a staffer to former prime minister Jim Bolger, is seen as a more centrist and pragmatic leader than Bridges.

Nikki Kaye, who was elected deputy party leader Friday, is from the Nationals' liberal wing.

A One News-Colmar Brunton poll released Thursday night put support for Ardern's Labour Party up 18 points at 59 percent, a record for the centre-left grouping.

Ardern's rating as preferred prime minister was 63 percent, up 21 points to the highest figure recorded by any lawmaker in the survey's 25-year history.

Bridges' support as preferred prime minister was just five percent.

A Newshub-Reid Research poll released Monday showed similar stellar support for Ardern, including 91.6 percent backing for the youthful leader's COVID-19 response.

Ardern, 39, put New Zealand in a strict seven-week lockdown that ended last week with the virus seemingly under control.

New Zealand, with a population of five million, has recorded only 21 COVID-19 deaths.