The 80s star, who is a former girlfriend of judge Simon Cowell, said she believes that Burke is the best contestant in the ITV competition.
"I would love Alexandra to win because I think she's amazing, won't embarrass us and will make us proud on the international stage," she is quoted as saying.
"But I believe Eoghan will win because he's cute and young and pretty. But I don't think he's the best contestant, actually."
Burke will perform Britney Spears's 'Toxic' on Saturday's live show.
The X Factor airs at 7.35pm and 10.15pm tomorrow on ITV1.