Register, or affiliate as a Republican
Registration and party affiliation are handled by the county clerk and the Colorado Secretary of State. This site cannot sign you up.
Start by checking the registration already on file. The record shows whether you are affiliated with a party or unaffiliated.
To register, or to change your affiliation to Republican, use the clerk’s instructions or the Secretary of State form. Affiliation deadlines for a primary or a caucus are set in state law and published on those official pages. This site does not restate the deadline, because a copied date goes stale.
If the Secretary of State page asks you to prove you are a person, that check belongs to the state site.