Simpson ran in Alberta's first provincial election in Innisfail as the Liberal candidate, and was elected over Conservative Sam Curry by a single vote—the narrowest margin of any race in the election. In the Legislative Assembly of Alberta, Simpson served as deputy speaker. During the Alberta and Great Waterways Railway scandal, he remained loyal to the government of Premier Alexander Cameron Rutherford in the face of a rebellion from Liberal insurgents. There was some concern on the government side that the speaker, Charles W. Fisher, would resign to support the insurgents; Simpson's elevation to speaker, a position which was expected to remain impartial, would rob the government of a crucial vote. After Rutherford's government fell, Simpson supported the successor government of Liberal Arthur Sifton, though its stance on the issue that had toppled Rutherford's government—the construction of the Alberta and Great Waterways Railway—was in many respects diametrically opposed to Rutherford's.