California Code, Elections Code - ELEC § 8081

Before any nomination document is filed in the office of the county elections official or forwarded for filing in the office of the Secretary of State, the county elections official shall verify the signatures and the political preferences, if required, of the signers on the nomination paper with the registration affidavits on file in the office of the county elections official.  The county elections official shall mark “not sufficient” any signature that does not appear in the same handwriting as appears on the affidavit of registration in his or her office, or that is accompanied by a declaration of party preference that is not in accordance with the declaration of party preference in the affidavit of registration.  The county elections official may cease to verify signatures once the minimum requisite number of signatures has been verified.