Jacinda Ardern prevails in final debate before New Zealand election

Leader says she will resign if not re-elected but polls show Labour 15 points ahead

Jacinda Ardern has dominated the final leaders' debate before New Zealand goes to the polls on Saturday, appearing confident and prime ministerial as she took on a subdued Judith Collins.

In a surprise admission, Ardern said if she was not re-elected, she would resign as Labour leader.