The 40-year-old Take That star is said to have been offered a contract worth £2million and according to Star magazine is just 'days away' from sealing the deal with the show's chief Simon Cowell.
A source told Star, 'Gary let it be known that he was definitely interested. The show's bosses are really keen on Gary - they know he is highly knowledgeable about music, and probably more reliable than Robbie [Williams].
'Simon [Cowell] really respects Gary - as far as Simon is concerned, he is the perfect person to mentor the groups - not only because of his experience within the industry but because he knows both sides of fame.'