California Code, Elections Code - ELEC § 8001

(a) A declaration of candidacy for membership on a county central committee shall not be filed by a candidate unless (1) at the time of presentation of the declaration and continuously for not less than three months immediately prior to that time, or for as long as the candidate has been eligible to register to vote in the state, the candidate is shown by the candidate's affidavit of registration to have expressed a preference for the political party of that committee, and (2) the candidate has not been registered with a preference for a qualified political party other than that political party within 12 months.

(b) The elections official shall attach a certificate to the declaration of candidacy showing the date on which the candidate registered with a preference for the political party of that committee, and indicating that the candidate has not been registered with a preference for any other qualified political party for the period specified in subdivision (a) immediately preceding the filing of the declaration.  This section does not apply to a declaration of candidacy filed by a candidate of a political party participating in its first direct primary election subsequent to its qualification as a political party pursuant to Section 5100.

(c) Notwithstanding subdivision (a), a county central committee, subject to the bylaws of the state central committee, may establish the length of time that a candidate for membership on that committee must be shown by the candidate's affidavit of registration to have expressed a preference for the political party of that committee, and may establish the length of time that a candidate for membership on that committee must not have been registered with a preference for a qualified political party other than the political party of that committee.