The city has started moving away from the automobile and towards mass transit. From 2004 to 2009, the annual number of unlinked public transportation trips increased by approximately 21%. In 2006, voters in King County passed proposition 2 (Transit Now) which increased bus service hours on high ridership routes and paid for five bus rapid transit lines called RapidRide. After rejecting a roads and transit measure in 2007, Seattle-area voters passed a transit only measure in 2008 to increase ST Express bus service, extend the Link Light Rail system, and expand and improve Sounder commuter rail service. A light rail line from downtown heading south to Sea-Tac Airport began service on December 19, 2009, giving the city its first rapid transit line with intermediate stations within the city limits. An extension north to the University of Washington is scheduled to open in 2016; and further extensions are planned to reach Lynnwood to the north, Des Moines to the south, and Bellevue and Redmond to the east by 2023. Former mayor Michael McGinn has supported building light rail from downtown to Ballard and West Seattle.

Answer this question, if possible (if impossible, reply "unanswerable"): Which former mayor backed the expansion of rail lines from downtown to Ballard?
Michael McGinn