A source said: ''Simon thinks Kelly and Kevin are unique picks, and after meeting with both of them, he believes they have perfect chemistry for co-hosting.
''He loves Kelly's sass, and thanks to 'Glee' Kevin is an accomplished talent. They bounce off each other brilliantly.''
However, Simon is still said to be considering other stars and is going over details before he makes a firm decision on who to hire.
The source told National Enquirer magazine: ''Simon is a fickle guy, and there are still kinks that have to be figured out before he's 100 per cent certain he'll hire Kelly and Kevin.''
Welsh presenter Steve Jones was fired of host of the show after just one series in a shake-up that also saw Paula Abdul and Nicole Scherzinger - who is now a judge on the UK version of the programme - dismissed.