Note that the Victorian Country Party at this election was split into two factions, the United Country Party, which was loyal to the state party, and the Liberal Country Party, loyal to the federal party and formed following John McEwen's expulsion from the UCP. The UCP elected one member and the LCP two.
Until the 1940 Canberra air disaster on 13 August, Menzies was not planning an election so early, as it was not due until December 1940 or even as late as January 1941. However, the loss of three Cabinet ministers meant that three by-elections would have been required, followed within a few short months by a general election. Bringing the general election on earlier than planned was the preferred solution.
Both the Coalition and Labor supported Australia's ongoing participation in World War II. The Coalition's advertisements asked Australians to "Cast Your Vote for Unity and an All-in War Effort / Back the Government that's Backing Churchill", with a large picture of the British Prime Minister. Labor promised "A New Deal / for the Soldier / for the Soldier's wife / Widows, the Aged and Infirm / the Taxpayer / the Working Man / the Primary Producer".