California Code, Government Code - GOV § 84100

(a) Every recipient committee, as defined by subdivision (a) of Section 82013, shall have a treasurer.  An expenditure shall not be made by or on behalf of a committee without the authorization of the treasurer or the treasurer's designated agents.  A contribution or expenditure shall not be accepted or made by or on behalf of a committee when the office of treasurer is vacant.

(b) A recipient committee, as defined by subdivision (a) of Section 82013, may designate one assistant treasurer on the committee's registration.  The assistant treasurer may sign and verify a campaign report on behalf of the committee if the assistant uses reasonable diligence to prepare and review the report and signs to that effect under penalty of perjury as required by Section 81004.