The Irish twins are currently competing alongside housemates including Amy Childs, Paddy Doherty and Tara Reid in the Channel 5 show.
The bookies currently have John and Edward Grimes as 11/8 favourites to win Brian Dowling's first series in charge of the programme. Katona is behind on 7/2, while My Big Fat Gypsy Wedding star Doherty has had his odds cut from 12/1 to 5/1 in the last 24 hours.
William Hill is also offering odds of 20/1 that Sally Bercow's husband John resigns as Speaker of the House of Commons due to her time in the house. The couple are 8/1 to announce that they are splitting before the end of the year.
Bercow has now attracted over 90% of early bets on this week's eviction. With odds of 8/1, she faces Katona and model Bobby Sabel in the first vote-to-save of the series.
"John Bercow's credibility as Speaker in the House of Commons is under threat and it is easy to see their relationship taking a tumble," a spokesperson said.
Celebrity Big Brother continues tonight at 10pm on Channel 5.
> Celebrity Big Brother denies housemates have iPod after Amy Childs comment
> Celebrity Big Brother: Sally Bercow facing 'gruesome' divorce
Watch Jedward and Amy Childs discuss Sally Bercow's job below: