Colo. Rev. Stat. § 31-10-507
In any ordinance adopted by the governing body of the municipality requiring an affidavit of intent for write-in candidates as provided in section 31-10-306, the governing body may also provide that, if the only matter before the voters is the election of persons to office and if, at the close of business on the sixty-fourth day before the election, there are not more candidates than offices to be filled at such election, including candidates filing affidavits of intent, the clerk, if instructed by resolution of the governing body either before or after such date, shall cancel the election and by resolution declare the candidates elected. If so provided by ordinance, upon such declaration the candidates shall be deemed elected. Notice of such cancellation shall be published, if possible, in order to inform the electors of the municipality, and notice of such cancellation shall be posted at each polling place and in not less than one other public place.
C.R.S. § 31-10-507