Supermodels Heidi Klum and Cindy Crawford are also rumoured to be in the running for the role, occupied by Hunter since 2004 when she replaced Rod Stewart's fiancee Penny Lancaster, according to Vogue.com.
A source says, "A decision will be made in the next couple of weeks. The current favourites are Eva and Nicollette - with Eva way out in front.
"The American connection is important as Ultimo is about to hook up with a big New York store. Rachel's modelling of Ultimo bras and lingerie has generated $32 million (GBP18 million) of publicity in two years. Having someone like Eva on board will double or treble that."