Jacinda Ardern's landslide election win gives her a mandate for the transformational change she has been promising New Zealand for three years, but the COVID-19 pandemic may limit what she can actually do.

The prime minister's signature achievement in all but eliminating the new coronavirus from the Pacific island nation through strict lockdowns propelled her to victory on Saturday. But this approach may also hinder the recovery New Zealanders are hoping for and the progressive policies Ardern champions.

The general election was "tectonic," and with this mandate, Ardern "needs to deliver", said Richard Shaw, professor of politics at Massey University.