Lancaster served as member of the Oregon Territorial Council (Senate) from 1850 to 1852. During the tumultuous 1851-52 session of the Oregon Territorial Legislature Lancaster gave his allegiance to a rump group consisting of four members of the House who refused to participate with the Democratic Party majority in session at Salem. Lancaster was the sole member of the Council who attempted to establish this minority faction as the legitimate Oregon Territorial Legislature in a session held at the Territorial Library in Oregon City. This rival minority assembly continued to meet in Oregon City for two weeks, time which was marked by the spectacle of Lancaster making and seconding his own motions in the "Council" himself.