In the 1986 special election for the Chicago City Council, Stewart ran against Robert Kellam, a white incumbent, in an eight candidate race in Chicago's 18th ward. She was endorsed by the Chicago Tribune and by Mayor Harold Washington. Stewart, viewed as the most viable African-American opponent to Kellum, ultimately lost the election receiving 4,720 (24%) to Kellum's 12,666 votes (64%). In the 1990 Democratic primary, she challenged incumbent Mary Flowers, losing in a four-way race.
