"There is no neighborhood in this city I am afraid to go to," Oakland Mayor Jean Quan said Wednesday in announcing her campaign for a second four-year term. Quan may be fearless in the city streets, but she's got some daunting opposition. She faces 20 challengers in November, including Councilwomen Rebecca Kaplan and Libby Schaaf, San Francisco State Professor Joe Tuman and civil rights attorney Dan Siegel. Quan also identified dozens of supporters, including Gary Yee, former Oakland schools chief, and San Francisco Mayor Ed Lee.