New Zealand's populist kingmaker Winston Peters backed centre-left opposition leader Jacinda Ardern to become prime minister Thursday after finally moving to break the country's general election deadlock.

The powerbroker's decision, made almost four weeks after the September 23 poll, gives Ardern's Labour Party the numbers to form a coalition government with Peters' New Zealand First and the Greens.

"We had a choice to make for a modified status quo or for change... that's why in the end we chose a coalition government of New Zealand First with the New Zealand Labour Party," Peters told reporters.