Cal. Elec. Code § 7100
In each year of the general election at which electors of President and Vice President of the United States are to be chosen, the candidate in each congressional district who received the largest number of votes in the primary election among the candidates who disclosed a preference for the Democratic Party shall designate one presidential elector and one alternate presidential elector for the purposes of Chapter 1.2 (commencing with Section 6911) of Part 2 of Division 6 and shall file each elector's name and residence and business address with the state chairperson by a date specified by the state chairperson. The candidate for United States Senate who received the largest number of votes in the primary election among the candidates who disclosed a preference for the Democratic Party in each of the last two United States senatorial elections shall designate one presidential elector and one alternate presidential elector and shall file each elector's name and residence and business address with the state chairperson by a date specified by the state chairperson. In the event there is no candidate for United States Senate or for any particular congressional district who disclosed a preference for the Democratic Party, or if any candidate fails to designate a presidential elector and alternate presidential elector by the date specified by the state chairperson, the state chairperson shall designate one presidential elector and one alternate presidential elector for each vacancy. The state chairperson shall file the names and residence and business addresses of all the electors designated pursuant to this section with the Secretary of State by October 1 of the presidential election year.
Ca. Elec. Code § 7100