Colo. Rev. Stat. § 31-10-1303
The contestor shall file in the office of the clerk of the district court, within ten days after the expiration of the period within which a recount may be requested pursuant to section 31-10-1207(2), or within ten days after the conclusion of a recount conducted pursuant to section 31-10-1207, whichever is later, a written statement of the contestor's intention to contest the election, setting forth the name of the contestor, that the contestor is a registered elector of the municipality, the name of the contestee, the office contested, the time of election, and the particular causes of the contest. The statement shall be verified by the affidavit of the contestor or some registered elector of the municipality that the causes set forth in such statement are true to the best of the affiant's knowledge and belief.
C.R.S. § 31-10-1303
This section is similar to former § 31-10-1103 as it existed prior to 1975.