In a statement released this morning, Cheney explained she was ending the campaign because of serious family health issues:
Serious health issues have recently arisen in our family, and under the circumstances, I have decided to discontinue my campaign. My children and their futures were the motivation for our campaign and their health and well being will always be my overriding priority.
Phil and I want to thank the thousands of people in Wyoming and all across the country who have supported my campaign. As a mother and a patriot, I know that the work of defending freedom and protecting liberty must continue for each generation. Though this campaign stops today, my commitment to keep fighting with you and your families for the fundamental values that have made this nation and Wyoming great will never stop.
Cheney announced her campaign less than six months ago in a YouTube video, which you can watch here. Her withdrawal all but guarantees Enzi a fourth term. Wyoming has not elected a Democrat to the Senate since 1970.
As you can see in the accompanying video, Cheney's campaign got of to a rough start and wasn't appreciated by the Republican elite. The very public family squabble between Liz and her lesbian sister Mary, about same sex versus traditional marriage cost Liz more points with the Republican elite struggling to re-brand the party.