A Berkeley physician officially kicked off his petition drive Friday to recall Gov. Arnold Schwarzenegger from office. Dr. Kenneth Matsumura announced the effort in September, but his petition was not approved by the secretary of state's office for circulation until Jan. 3. Matsumura claims he has about 10,000 volunteers statewide willing to help gather signatures, and he is urging them to step lively so a recall can coincide with the June primary. Riverside County Democratic Central Committee Chairwoman Shirley Walton is among those volunteers, although the party itself has taken no stance on Matsumura's effort.