Free Vectorsswiss holding companyIn May 1912, Sifton expanded his cabinet, and Stewart was made the province's first Minister of Municipal Affairs.[6] As was required by the custom of the day when an MLA was appointed to cabinet, he resigned his seat to run in a by-election, in which he easily defeated Conservative William John Blair.[7] In cabinet, he became known as an advocate of public ownership of utilities, which placed him more in sympathy with the Conservative opposition than with Sifton.[8] Despite this position, he backed Sifton's 1913 resolution to the Alberta and Great Waterways problem, which involved partnering with the private sector; this vote marked the first time that the Liberal caucus was united on the railways question since before the scandal broke in 1910.[9]
In December 1913, Sifton moved Stewart from Municipal Affairs into the Public Works portfolio; in this capacity, Stewart played a major role in the incorporation of the Alberta Farmers' Co-operative Elevator Company,[8] which was a farmer-run co-operative with a charter to own and operate grain elevators.[10]