Colorado Revised Statutes Title 31. Government Municipal § 31-10-1301. Who may contest--causes

(a) When the contestee is not eligible for the office to which he has been declared elected;

(b) When illegal votes have been received or legal votes rejected at the polls in sufficient numbers to change the results;

(c) For any error or mistake on the part of any of the judges of election or the clerk and his assistant in counting or declaring the result of the election if the error or mistake would be sufficient to change the result;

(d) For malconduct, fraud, or corruption on the part of the judges of election in any precinct or any clerk or his assistant if the malconduct, fraud, or corruption would be sufficient to change the result;

(e) For any other cause which shows that another was the legally elected person.