Deputy Prime Minister of Australia accepted the view put to him by McEwen that to commission a Liberal temporarily as Prime Minister would give that person an unfair advantage in the forthcoming party room ballot for the permanent leader. McEwen's appointment was in keeping with the previous occasion when the main non-Labor party was without a leader; Earle Page of the Country Party was interim Prime Minister between 7 and 26 April 1939—the period between Joseph Lyons' sudden death and the United Australia Party naming Robert Menzies his successor. Since 1968 only two Deputy Prime Ministers have gone on to become Prime Minister: Paul Keating
Acting prime minister as Prime Minister, until a colleague of higher rank is available again. Acting prime minister An acting Prime Minister is a cabinet member (often in Westminster system countries) who is serving in the role of Prime Minister, whilst the individual who normally holds the position is unable to do so. The role is often performed by the Deputy Prime Minister (where that position exists), or by another senior Minister. The office is commonly used when the Prime Minister is absent from the territory of that nation, when the Prime Minister is in ill health or, on maternity leave. An acting