As part of this, he proposed the title "Commonwealth of Australia". As a moderate Protectionist, but with the endorsement of the conservative Australasian National League (formerly National Defence League), Playford became a Senator at the inaugural 1901 federal election. Two years later in Alfred Deakin's government, Playford served for seven months as Leader of the Government in the Senate and Vice-President of the Executive Council. He became Minister for Defence in 1905 which he held for 18 months. He was defeated in the 1906 federal election, the first serving Minister to suffer this fate. His term as a Senator ended on 31 December 1906, and his ministerial commission was terminated on 24 January 1907. Playford made one further unsuccessful attempt to re-enter the Senate at the 1910 federal election. Playford died in Kent Town, Adelaide on 19 April 1915. Playford married Mary Jane Kinsman (born 20 May 1835, the daughter of Rev. William Kinsman) on 16 December 1860. The couple had eleven children: five sons, five daughters and one adoptive daughter. His eldest daughter Annie (died 1956) married the Rev. John Henry Sexton on 30 June 1886. On 1 January 1889 his second daughter Eliza (born 1866) married Harry J. Tuck (born 1863), elder brother of painter Marie Tuck and later headmaster at Unley High School. Playford's grandson, Sir Thomas Playford, also served as Premier of South Australia.