Colo. Rev. Stat. § 1-13.5-1403
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 1-13.5-1306, or within ten days after the conclusion of a recount conducted pursuant to section 1-13.5-1306, whichever is later, a written statement of the contestor's intention to contest the election and setting forth the name of the contestor, that the contestor is an eligible elector of the local government, the name of the contestee, the office contested, the time of election, and the particular causes of the contest. The statement must be verified by the affidavit of the contestor that the causes set forth in the statement are true to the best of the affiant's knowledge and belief.
C.R.S. § 1-13.5-1403