Government Code § 3207
CHAPTER 9.5. Political Activities of Public Employees
Any city, county, or city and county charter or, in the absence of a charter provision, the governing body of any local agency and any agency not subject to Section 19251 by establishing rules and regulations, may prohibit or otherwise restrict the following:
(a) Officers and employees engaging in political activity during working hours.
(b) Political activities on the premises of the local agency.