Kara DioGuardi is following Ellen DeGeneres and Simon Cowell out the door at “American Idol.” Her departure leaves Randy Jackson, who's been with the singing contest from the start, the last judge standing, for now. Steven Tyler and Jennifer Lopez are the reported front-runners for the panel. Entertainment mogul Simon Fuller, creator of the British show “Pop Idol” that was the template for the US series he produces, called DioGuardi a standout songwriter whom he planned to work with in music “for many years to come.” DioGuardi, whose exit had been rumored, is a hit machine whose songs have been recorded by Gwen Stefani, Faith Hill, Marc Anthony and others, including past “Idol” winners. “I felt like I won the lottery when I joined `American Idol' two years ago, but I feel like now is the best time to leave `Idol,”' DioGuardi said in a statement Friday, calling her experience as a judge on the show “amazing.” Her statement, issued by Fox, didn't elaborate on her reasons for leaving. Her contract reportedly had a one-year option remaining that the network could have exercised. Although she offered informed critiques on “Idol,” observers faulted her for lacking the pizazz - and unpredictability - that ex-judge Paula Abdul had provided.