Undoubtedly, De Cosmos' reputation as an iconoclast and his infamously volatile temperament did not endear him to the establishment. McCreight resigned in 1872 on a motion of non-confidence, and on December 23, 1872, Trutch asked De Cosmos to form a new government as Premier. De Cosmos populated his cabinet with reformers, mostly born in North America, many of whom would come to dominate provincial politics for the generation. His government pursued an agenda of political reform, economic expansion, and the development of public institutions — especially schools. De Cosmos also focused on advancing the completion of the transcontinental railway promised under the Terms of Union. It was, however, De Cosmos' attempt to alter the Terms of Union in order to obtain monetary guarantees from the federal government to complete a dry dock at Esquimalt that eventually led to accusations of impropriety, and ended his provincial political career. He speculated heavily in land and in Texada Island iron mines, which brought further criticism, as he was a public official. Thus he ended his tenure as Premier on February 9, 1874. Despite this setback, De Cosmos continued to be re-elected as a Liberal Member of Parliament for Victoria City. Consistent with federal promises to place the terminus of the transcontinental railway in Victoria, in Ottawa, De Cosmos pushed for completion, especially the Vancouver Island portion. De Cosmos also became an opponent of land concessions to First Nations in the province, seeing it as a hindrance to British Columbia's economic growth and settlement by those of European descent. It is generally conceded that De Cosmos's tenure as a member of the dominion parliament was undistinguished. De Cosmos lost the 1882 federal election and retired to Victoria. Although widely regarded as a stirring orator, master debater, and a man of great intellectual depth, De Cosmos had always been considered eccentric. Contemporaries paint a portrait of an isolated person (he never married and had few intimate friends; some claimed he had a daughter from a friend he met) with grandiose manners, prone to public outbursts of tears, and a fierce temper that sometimes degenerated into fist-fights. He had unusual phobias — including a fear of electricity. As he grew older, his eccentricities intensified, he became increasingly incoherent. By 1895 he was declared insane. One of his more notable eccentricities was the founding of a hot food delivery company to prospectors in the Klondike Gold Fields. The difficult logistics of this service scared away investors and ultimately provided its downfall.