The former judge and executive producer is said to have labelled the singer as "dated and cheesy", and has launched a secret plot to try and remove him from the competition.
Cowell has reportedly asked judges Louis Walsh, Tulisa Contostavlos and Nicole Scherzinger to heavily criticise the 34-year-old in the hopes of convincing the public not to vote for him.
"Chris winning or even getting further into the competition is a disaster for Cowell," a source told The Mirror.
"He wants Chris out and the fact that his mentor is Gary Barlow makes him even more desperate to get him kicked off."
Simon Cowell and Gary Barlow have recently been rumoured to have a rivalry behind the scenes, with Cowell said to have been angry at Barlow's OBE.
Chris Maloney has been reported to have topped the votes in the first two weeks of The X Factor, ahead of bookmakers' favourite Ella Henderson.
Watch Christopher Maloney talk to Digital Spy below: