The 32-year-old performer was a guest judge on the UK version of the show earlier this year after Cheryl Cole was taken ill with malaria.
Cheryl, 27, was recently reported to have signed a deal securing her place on the US version of the show when it is started next year.
It is claimed boss Simon Cowell, 51, wants both ladies on the judging panel with him.
A source said to UK newspaper The Sun: 'The US team want both women going up against each other.'
Pregnant singer Mariah Carey was also rumoured to be in the frame for a judging role.
A spokesman for the show reportedly refused to comment on the new reports.