Chris Daughtry said he and fellow "American Idol" alum Adam Lambert are returning to the U.S. reality series to serve as mentors. The two former winners have signed on to walk contestants through a new phase of the competition called Randy Jackson's Boot Camp, the Hollywood Reporter said Saturday. The top contestants have to make it through the workshop before they can perform before an audience. Daughtry first announced his return to the show on Twitter. "Hanging with @Adamlambert at the #idol workshop. Glad to be back! Stay tuned ... ," he wrote.