With Ferrero on the sidelines, Hershey, which considered a joint bid with it, has now become more isolated in its ability to launch a bid to counter Krafts Foods.
Both Ferrero and Hershey are smaller than Cadbury and would need to raise significant financing to launch an offer.
The two companies were reportedly in talks with the private equity firms Blackstone Group and Kohlberg Kravis Roberts (KKR).
Another prospective bidder Nestle has pulled itself from the auction.
Members of the Cadbury board have been talking with counterparts at Hershey as expectations fade for a significantly higher bid from Kraft.