 Nyora kupfuurira kweiyi ndima - Muna 1966, Menzies akarega basa uye akatsiviwa somutungamiriri wehurumende naHarold Holt. McMahon akabva atora nzvimbo yaHolt semutevedzeri wemutungamiri weLiberal Party. Akagadzwa kuva Treasurer muHolt Government, uye mumakore matatu akatevera akatarisira kuderedzwa kukuru kwehurombo hwenyika. Pashure porufu rwaHoltmuna 1967, McMahon aida kukwikwidza hutungamiri hweLiberal asi akanga achirambwa naJohn McEwen, mutungamiri weCountry Party. Mutungamiriri wehurumende mutsva akanga ari John Gorton. Pakutanga McMahon akaramba ari Treasurer muHurumende yeGorton, asi muna 1969 akaderedzwa kuva Gurukota rezvekunze mushure mekupokana kusingabudirire kwehutungamiriri. Iye pakupedzisira akamanikidza kusiya basa kwaGorton mukutanga kwa1971, achikunda vhoti pamusoro paBilly Snedden. 