There’s no harmony on the American Idol set as Lionel Richie and Luke Bryan clash over who should replace exiting judge Katy Perry on ABC’s hit singing competition, insiders exclusively tell Life & Style. “It’s turning into a real claw-fest now that Katy’s leaving,” one source reveals.

The “I Kissed a Girl” singer, 39, recently announced her departure from the show so she can return to her “day job” making music. Since then, Luke, 47, and Lionel, 74, have been feuding over who should fill her seat. “This has been a very stressful time for Luke and Lionel because they’ve been left in the dark about so much — there was even talk producers were going to start fresh with a whole new lineup and give them the boot,” the insider says. “That hasn’t happened, so now the next worry is who will join the show.

“Luke’s complaining Lionel’s trying to insert one of his favorites and hijack the show,” the source says. “Luke thinks the decision isn’t up to them, it’s the bosses who should decide, and he’s irritated that Lionel’s being so pushy behind the scenes.”

The “All Night Long” singer openly admits he wants a friendly face to join them at the judges’ table. “I do have my eye on at least two,” Lionel has said. According to our insider, “Lionel is constantly putting his two cents in to sway producers and saying they should get someone like Diana Ross, Kenny Chesney or Tim McGraw — if they’d agree to do it. “All of them have collaborated with Lionel over the years and Luke thinks even if they agreed, it would put Lionel at an unfair advantage over him.”

But producers are actually said to be welcoming the nonstop squabbling. “The bosses don’t seem to mind it,” dishes the source. “Their tension helps the competition on the show.”