A system of electing supervisors by district rather than citywide took effect in 2000. At the urging of Supervisor Tom Ammiano, Gonzalez moved from his home in the Mission District to run for supervisor in newly made District 5. In early November, shortly before the run-off election, Gonzalez switched party affiliations from the Democratic Party to the nascent Green Party. His opponent, Juanita Owens, tried to capitalize on many Democrats' ill feelings toward the Green Party in the wake of Ralph Nader's involvement in the acrimonious 2000 presidential election, but Gonzalez won the run-off election. He was part of a slate of candidates who wanted to change the direction of city policy, in opposition to the "Brown machine," a Democratic Party political machine that had dominated local politics for over 30 years behind Mayor Willie Brown, the Pelosi family, and other Democrats. His supporters saw his election as a turning point in local politics.