2018 San Francisco mayoral special election
Ed Lee, who was appointed Mayor of San Francisco in 2011 following Gavin Newsom's election as Lieutenant Governor of California, elected to a full term in 2011, and reelected in 2015, died of cardiac arrest on December 12, 2017. London Breed, the President of the San Francisco Board of Supervisors, became the city's acting mayor.
2003 San Francisco mayoral election
In 2003, then-Supervisor Gavin Newsom, a Democrat, ran in a large field of challengers, including Board of Supervisors President Matt Gonzalez, Supervisor Tom Ammiano, former Supervisor Angela Alioto, city Treasurer Susan Leal, and former Police Chief Tony Ribera. Newsom and Gonzalez took first and second place, respectively, but neither won a majority, so the two advanced to a runoff election. Third party advocates saw it as a chance to dethrone the Democratic Party.