Colorado Revised Statutes Title 1. Elections § 1-13.5-1401. Person elected--contest--causes

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

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

(c) An error or mistake was made by any of the election judges, the designated election official, or the canvass board in counting or declaring the result of the election, if the error or mistake was sufficient to change the result;

(d) Malconduct, fraud, or corruption occurred on the part of the election judges in any polling place, a canvass board member, or any designated election official or his or her assistant, if the malconduct, fraud, or corruption was sufficient to change the result; or

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