The Labour Party had formed its first ministry after winning the 1935 election, and had remained in power (with gradually decreasing majorities) since then.

The National Party, formed by a merger of the parties which Labour had originally ousted, gradually increased its power in Parliament; the ineffectual Adam Hamilton was replaced by Sidney Holland, and internal disputes were gradually resolved.

Ongoing shortages after World War II also eroded public support for the government.

The National Party's decision not to repeal Labour's social welfare policies also increased its appeal.

John A. Lee stood for Grey Lynn as the sole Democratic Labour candidate and got 2,627 votes, coming third.