The National Party had been in office since the 1960 elections, when it had defeated the ruling Labour Party, led by Walter Nash. The Second Labour Government was the shortest-lasting of all New Zealand governments to that day; in contrast, the Second National Government, led for the majority of its tenure by Keith Holyoake, would be re-elected three times. National's policies were focused around stability and a "steady as she goes" approach, but Holyoake's Government was increasingly perceived as tired and worn-out. In February 1972, Holyoake stood aside and was replaced by his deputy, Jack Marshall, who took steps to reinvigorate the party.
Meanwhile, Norman Kirk had been at the helm of Labour since 1965. In this time, he had been modernising and updating the Labour Party, but narrowly lost the 1969 election. Kirk slimmed and dressed to improve his image, and visited several overseas Labour parties to broaden his knowledge. He activated a "spokesman" or shadow cabinet system to spread the responsibility, though it was difficult to avoid one composed largely of Auckland and Christchurch members. Despite these improvements, commentators speculated whether National would pull off another cliff-hanger victory. Economic recession and voter fatigue hurt National at the polls. Labour's solgan was 'Time For A Change-Vote Labour', which expertly captured the national mood.
Since the 1969 elections, the number of electorates in the South Island was fixed at 25, with continued faster population growth in the North Island leading to an increase in the number of general electorates. Including the four Māori electorates, there had been 80 electorates since the 1902 elections. This increased to 84 electorates through the 1969 election. The 1972 electoral redistribution saw three additional general seats created for the North Island, bringing the total number of electorates to 87. Together with increased urbanisation in Christchurch and Nelson, the changes proved very disruptive to existing electorates. Only two South Island electorates were not altered by the redistribution (Clutha and Lyttelton). Only eight of the North Island electorates were not altered (Franklin, Gisborne, Hobson, Island Bay, Miramar, North Shore, Tamaki, and Wairarapa).
The date for the 1972 elections was 25 November, a Saturday. 1,583,256 people were registered to vote, and there was a turnout of 89.1%. This turnout was slightly higher than the previous election, and considerably higher than the following one. The number of electorates being contested was 87.