The left has already won this election.
John Key's National Party is still high in the polls, not because the values of the right are popular, but because National's pitch is essentially, "Trust us to implement Labour policy. We'll spend a bit less than them doing it, and if you're lucky we'll give you a tax cut from the savings -- maybe."
The left won the contest of ideas a long time ago, and National has completely capitulated. It wouldn't dare reverse Labour policies such as state-funded education and health care, Working for Families tax credits, interest-free student loans or KiwiSaver.
Almost everyone working for wages today owes something to the Labour movement, including the trade unions, from the 40-hour week to public holidays.
The right fought these attempts to improve working conditions. But change was popular. The left won.