The Hollywood couple were recently rumoured to be the favourites to host the talent show when music mogul Simon Cowell takes it to the US next year.
A report in UK newspaper News Of The World claimed the British host Dermot O'Leary was being overlooked for a role on the US show.
An insider claimed: 'Dermot will be completely distraught. He spent months in America lobbying to get this job. He held out a lot of hope.
'But he can't compete with Zac and Vanessa. They are two of the biggest stars in the States and will make American X Factor the biggest show in the world.'
However a rep for Hudgens has denied the report to Gossip Cop and said the rumours about the pair of them hosting the show are 'not true'.