Colorado Revised Statutes Title 1. Elections § 1-2-219. Changing or withdrawing declaration of affiliation

(1) Any eligible elector desiring to change or withdraw the elector's affiliation may do so by completing and signing a prescribed request for the change or withdrawal and filing it with the county clerk and recorder or by submitting a personal letter written by the elector to the county clerk and recorder at any time up to and including the twenty-second day preceding a primary election;  except that, if the twenty-second day before the primary election is a Saturday, Sunday, or legal holiday, the change or withdrawal applies if made by the next day that is not a Saturday, Sunday, or legal holiday. The prescribed form or personal letter for the change must include the elector's printed name, address within the county, birth date, the last four digits of the elector's social security number, if the elector wishes to state it, and signature, the date, the elector's previous affiliation status, and the requested change in affiliation status. A prescribed form must be furnished by the county clerk and recorder upon the elector's oral or written request. Upon receiving the request, the county clerk and recorder shall change the elector's affiliation on his or her registration record. If the affiliation is withdrawn, the designation on the elector's registration record must be changed to “unaffiliated”. If an elector changes affiliation, the elector is entitled to vote, at any primary election, only the ballot of the political party to which the elector is currently affiliated. A change or withdrawal of affiliation may not be made by anyone other than the elector. Notwithstanding any other provision of law, a declaration or change of affiliation made by an unaffiliated elector in accordance with this section must be deferred if the elector has already been mailed a primary election ballot packet. The deadline by which the elector must declare, change, or withdraw an affiliation as specified in this subsection (1) only applies to a primary election and does not apply to a general or coordinated election.

(2) Any declaration, change, or withdrawal of affiliation made on the same form or personal letter as an address or name change shall be accepted by the county clerk and recorder if the form or personal letter is dated and signed so that it is clearly indicated that the elector intended to make the change or withdrawal indicated on the form or in the personal letter. An elector who is unable to write may request assistance from the county clerk and recorder, and the county clerk and recorder shall sign the form, witnessing the elector's mark or, on a personal letter, the elector shall have his or her signature attested to by a notary public.