Jennifer Lopez is the second judge in two days to say she's leaving "American Idol." Lopez will not be back for a third year on television's top-rated but struggling show, her representative, Mark Young, said Friday. Aerosmith frontman Steven Tyler announced Thursday he was exiting. That means the "Idol" panel is down to one, original judge Randy Jackson, and there are reports that he may take a different role when the Fox show returns next January.