In this Nine News footage from 18 December 1967, journalists interview Deputy Prime Minister John McEwen and then Treasurer William McMahon as they arrive at Parliament House.
Even before Holt disappeared, there was tension between McEwen and McMahon over economic policies. With Holt missing, McEwen was commissioned as prime minister until the governing parties appointed a replacement. He held the position for three weeks, from 19 December 1967 until 10 January 1968, when the Liberals elected John Gorton as their new leader. McEwen had threatened the Country Party would quit the Coalition if McMahon became the Liberal leader.
Gorton survived a challenge from McMahon and other contenders in 1969 but effectively handed the leadership to McMahon in 1971 after a vote of no-confidence. McEwen left parliament five weeks before McMahon replaced Gorton as prime minister.