He was a New Democratic member of the Legislative Assembly of Manitoba from 1966 to 1981, and held a number of high-profile cabinet portfolios in the government of Edward Schreyer.
In 1968–69, Cherniack and Miller played a significant role in convincing federal Member of Parliament Edward Schreyer to replace Russell Paulley as leader of the provincial NDP.
[1] As the former mayor of a suburban community, Miller was one of the few prominent New Democrats in Manitoba to oppose the party's call for a united City of Winnipeg at their 1968 policy convention.
When the legislation was defeated in a free vote, Miller and Schreyer made arrangements for specific denominational schools to receive provincial money by working in conjunction with the public system.
This policy was never enacted, however, due in part to Miller's concerns that it would label the NDP government as radically socialist and deplete its popularity.
Miller helped launch pharmacare and student aid, but often said that his greatest satisfaction was “being in the first NDP cabinet in Manitoba.” In 1977, he received the Queen Elizabeth II Silver Jubilee Medal.
The NDP lost government in the provincial election of 1977, and Miller was personally re-elected[1] over Progressive Conservative candidate Carl Zawatsky by only 820 votes.