Between 1968 and 1972, Lynch served variously as Minister for the Army, Minister for Immigration, and Minister for Labour and National Service, under Prime Ministers John Gorton and William McMahon. In opposition from 1972 to 1975, he was Deputy Leader of the Liberal Party. He was also the Deputy Leader of the Opposition as then Liberal leader Billy Snedden had refused to give the title to the Country Party leader Doug Anthony. After his party won back government in 1975, Lynch continued as Deputy Leader of the Liberal Party until his retirement in 1982.