Rick Renzi, the Republican incumbent in AZ-01 managed to keep his seat in 2006 following a vicious campaign against his Democratic challenger, Ellen Simon. Renzi, as you know, was a key player in the U.S. Attorney firings stemming from DOJ investigations into shady land deals orchestrated by the Congressman.
Desperate to keep his seat, Renzi ran slanderous ads against Simon calling her a "NAMBLA lawyer" (which she is not) and at one point calling her "the devil." Ellen Simon bowed out of the 2008 race, leaving the field open to a new Democratic challenger. But nobody's really stepped up.