The Glee star had reportedly turned down an X Factor job earlier this month due to scheduling problems, but Cowell dismissed those rumours to Access Hollywood.
"Darren Criss? I don't know who he is," Cowell admitted. "Is he the one in the wheelchair? I like him."
Cowell went on to say that his focus right now is to hire judges rather than a host.
"At the moment, all the concentration is on the judging panel. I've got to be honest with you... this is all gonna happen at the last minute," he predicted. "I can feel it… There's so much going on at the moment over there with the show."
He continued: "It's a lot of work to put in, and there's a new component to the show which is exciting and I'm not going to talk about it yet 'cause I don't want to tell the others what I'm doing. So there's just a lot going on.
"So I think in terms of order, we've got to land the judges, and then, I think you've gotta work out the hosts, based on who the judges are gonna be to make sure you get the right chemistry."
First season X Factor judges Nicole Scherzinger and Paula Abdul's departures have left two seats open on the judging panel.
Fergie, Britney Spears, LeAnn Rimes and Billy Corgan have all been linked to a judging role on the Fox reality competition.
The second season of The X Factor USA airs on Fox in September. Auditions are under way now, with further details available at www.thexfactorusa.com.
> Stacy Keibler in the running for X Factor USA role?
> Beyoncé would never judge X Factor USA, says father Mathew Knowles