Simon Cowell believes that Demi Lovato and Britney Spears are "feverish" judges on X Factor.

The music mogul, the two pop songstresses and producer L.A. Reid all sit on the judging panel of the US TV talent show.

Britney and Demi are new to their posts and Simon is thus far very happy with their critical approach.

"[They are] doing the best they can," he told X17 Online. "I've worked with much harder. Honest to god they are doing the job we paid them to do, and they are doing a great job. They are both, albeit feverish, but we hired them for that. They are trying to find a star, and give constructive advice. They ought to be my mentor."

Simon recognises that both Demi and Britney are ardent about discovering the next big star.

"They've both been child stars. They want to find somebody else, and I'm very impressed with them," he shared.

The X Factor team is currently traveling across America hosting auditions.