'American Idol' producers secretly plotted to 
replace Mariah Carey with Jennifer Lopez

Bosses were keen to see the return of 'On the Floor' singer Jennifer midway through the show's current season but, sources tell The Hollywood Reporter, once they were threatened with legal action by Mariah's team they backed off.

The insiders added a search has already begun to replace Mariah, Nicki Minaj and possibly even the entire judge's panel - which also includes Randy Jackson and Keith Urban - for the next season.

Mariah was a huge signing for the show, but has proved less popular with viewers on the show than Jennifer, who appeared in the previous two seasons, was. Mariah's comments and criticism have been criticised as passive and disengaged, and she has been overshadowed by Nicki on the show.

However, another source says research has shown Nicki's performance on the show has not been as popular as expected, adding: "The core viewer is a Midwestern, Southern, older woman who is threatened by Nicki's aggressiveness."

'American Idol's ratings have suffered this season, with its Wednesday show getting the worst ratings since the show began in 2001. In contrast, rival show 'The Voice' is riding high in the ratings due in part to boasting Shakira and Usher on its judging panel.

Official sources have denied any attempt to replace Mariah on the show.

A Fox spokesperson said: "This is just another ridiculous 'Idol; judge rumour, likely started by talks of Jennifer performing on the finale."

'American Idol' producer Nigel Lythgoe said: "I have not been included in any conversation regarding replacing Mariah with Jen this season."