The former X Factor Australia boss joined America's Got Talent earlier in this year, but could still appear on our X Factor too.
According to The Sun, Mel is 'Plan B' if Nicole Scherzinger refuses to agree on a deal.
It was reported last month that Nicole was holding out for more money, while she was also worried about how taking on the six month commitment would impact her relationship with Lewis Hamilton.
“Nicole and Lewis have the utmost respect for one another’s careers and will go out of their way to be there on big occasions,” an insider claimed. “But with most of the races in October, November and December outside Europe, they are genuinely going to struggle to meet up.
“Lewis has said to Nicole this is going to be an awful situation and perhaps she shouldn’t do it.”
With less than a month until auditions with the judges are due to kick off, it's left producers looking at their options again.
Gary Barlow and Louis Walsh are both now widely expected to be back, while Sharon Osbourne is also understood to have tentatively agreed a deal, although no contracts have yet been signed.
“Nicole is causing some worry. Bosses want her after her success last year, but she doesn’t know if she can give all her energy to the show," a source said. “Producers don’t want to be left in the lurch like last year so Mel is being lined up in case talks fail.”
Last year's show saw a range of guest judges stand in during the auditions after bosses failed to sign a new judge in place of Kelly Rowland.