He was the Member of Parliament for Dunedin Country from 1860 (after a by-election), then Bruce 1861 to 1865; two electorates in the South Island. While he had been a cabinet minister in the Domett Ministry (August 1862) and then the Whitaker–Fox Ministry (October 1863 – November 1864), he was a strong separationist, but did not get majority support in the ministries or from parliament as a whole, and he resigned his parliamentary seat in early 1865 as he could not achieve separation of the South Island. He first talked about having resigned in public on 6 January 1865 but the resignation did not take effect until 3 March of that year.