Stephanie Burns and Ben Parkinson strolled down sun-drenched Fillmore Street with political thievery on their minds. Both are grass-roots volunteers for Republican presidential contender Ron Paul, a Texas congressman whose libertarian views might seem to make him a tough sell in this legendarily left-wing city. But Burns, Parkinson and other Paul supporters have been spending their weekends marching, staffing tables and knocking on doors in an improbable quest: picking up some of California's 173 convention delegates in the Feb. 5 primary. On the surface, the plan seems quixotic given general assumptions about California: that the state is too big for...