The 41-year-old, whose husband John is speaker of the House of Commons, faces elimination alongside Kerry Katona and model Bobby Sabel.
Bookies William Hill now have Bercow as the 4/9 odds-on favourite to become the first housemate to exit the famous house. Sabel is offered at 13/8, while Katona is currently 25/1 to lose the first vote to save.
While Bercow has dismissed claims that taking part in the series could damage her marriage, the odds on the couple announcing a split by the end of the year now stand at 5/1.
"One person that you can guarantee will not be voting to keep Sally in the house is her husband John, who might just have got away with his career intact despite the odd indiscreet revelation!" said a spokesperson for William Hill.
Jedward remain 2/1 favourites to win Channel 5's first Celebrity Big Brother. Katona (9/4), Paddy Doherty (7/2), Amy Childs (6/1) and Lucien Laviscount (12/1) follow behind. Mr Paparazzi's Darryn Lyons is currently 50/1 to triumph.
Celebrity Big Brother continues tonight at 10pm on Channel 5.
> Celebrity Big Brother: Marco Pierre White to enter house for task?
> Celebrity Big Brother: Darryn Lyons rants at Amy Childs over task outfit
Watch Jedward as the Munchkins during the Celebrity Big Brother shopping task below: