Although Simon Cowell previously said he hoped to keep the same judges as last year for this autumn's series, Nicole Scherzinger has yet to sign up.
A source told The Sun previously: "She loves the show and ended last year indicating she’d be seeing them all same time, same place. But the longer things hang in the air, the more nervous people become.
“Filming is starting in June and and production will sleep easier when she gives Simon her answer.”
Speaking to the Sunday Mirror newspaper last month, Nicole confirmed she had been asked back to The X Factor this year but hadn't decided to say yes just yet.
She declared: "I don't know yet. We’ll see."
Nicole went on: "I might [be back on X Factor]. But I want to get back to creating. Last year I did a lot of TV and I loved it, but I didn’t spend time with the artist in me.
"The idea of doing that excites me more than anything."
Now it's been suggested that Mel B could be lined up to step in if Nicole fails to return.
Mel was a judge on the 2014 series, a guest judge in 2012 and has also made appearances on the panels of The X Factor Australia and America's Got Talent.
However more recently she's been in the papers because of her on-going divorce battle.
“Simon has got a massive soft spot for Mel and just wants to see her happy and doing well, especially given what is going on in her private life," a source told the Daily Mirror newspaper.
The X Factor will air on ITV in the autumn.