In the 1999 Ontario provincial election, Sewell ran as an independent candidate in the riding of Toronto Centre--Rosedale, challenging Progressive Conservative cabinet minister Al Leach to protest the megacity. His entry into the race was controversial, with many activists accusing him of splitting the left-wing vote with the New Democratic Party (NDP). Sewell was also criticized for remaining in the race after Leach, whom he had personally targeted as the minister responsible for amalgamation, withdrew from the contest. The riding was ultimately won by Liberal George Smitherman; Sewell finished third, behind Tory Durhane Wong-Rieger.