Cal. ELEC § 10512

(a) Each candidate shall set forth in full the oath or affirmation set forth in Section 3 of Article XX of the California Constitution, which shall be filed with the declaration of candidacy. The county elections official or district secretary, or a person designated by the county elections official or district secretary, shall administer the oath. (b) The county elections official or district secretary, or a person designated by the county elections official or district secretary, may administer the oath or affirmation set forth in Section 3 of Article XX of the California Constitution to the candidate elected to office.