Boris Johnson - will be stay or will he join campaign to leave the EU
Bookies are taking bets on whether the flaxen haired Tory will be an 'Inner' or an 'Outter'
A bookmakers has announced it will not cut its odds on Boris Johnson joining the Leave Campaign, despite strong rumours of him planning to rebel against Prime Minister David Cameron.
Star Sports is offering odds of 1/2 for Boris is back the Remain Campaign, and 6/4 that he campaigns to exit the EU.
Star Sports spokesman Jamie Loughead said they were confident Boris will side with the Remain campaign,
"Despite all the press coverage for Boris supposedly planning to become an 'Outter', we are confident there will be no Borxit," he said.
"We’re sure that the last few months of flirting with the Leave Campaign have been nothing but spin, and he’ll bottle it.”
"We’re the only bookmaker offering odds on which side Boris will support, and are happy to take even the shrewdest political punters on."
Prime Minister David Cameron has issued a last-ditch appeal to Boris Johnson not to join the campaign for Britain to leave the European Union.
With the London mayor set to end months of speculation over which side he will back, Mr Cameron said it would be a "wrong step" for Mr Johnson to link up with Ukip leader Nigel Farage and Respect's George Galloway in the "out" camp.
"I would say to Boris what I say to everybody else, which is that we will be safer, we will be stronger, we will be better off inside the EU," the Prime Minister told BBC1's The Andrew Marr Show.
"I think the prospect of linking arms with Nigel Farage and George Galloway and taking a leap into the dark is the wrong step for our country.
"If Boris and if others really care about being able to get things done in our world, then the EU is one of the ways in which we get them done."
Meanwhile Mr Johnson's sister has insisted her brother is not "milking" his decision over Britain's membership of the European Union for "maximum publicity".
Writer and broadcaster Rachel Johnson said her brother had to make a "very, very hard" choice as there are good and bad arguments on both sides.
She added Mr Johnson's presence in either the Remain or Leave campaign will be "very significant" - which is why he is taking so long to decide.
The London mayor is expected to reveal his intentions at 10pm on Sunday.
Ms Johnson also dismissed suggestions from presenter June Sarpong, of Britain Stronger in Europe, that it would be the "ultimate betrayal" to London if the city's mayor decides to support Britain's exit from the EU.
Ms Johnson told Murnaghan on Sky News: "I think that June's absolutely wrong to talk about this being an ultimate betrayal, and this is not in any sense Boris milking his decision for maximum publicity.
"This is an enormously complicated decision for everybody, not just Boris... and his participation in either camp is going to be very significant, and this is why he's taking so long to decide.
"The deal came through on Friday and perhaps you can imagine it's a very, very hard choice that he has to make, and in fact it's a hard choice for everybody to make because there are good and bad arguments on both sides."
She added: "I have spoken to him, yes, and he will let everybody know his decision in his Daily Telegraph column, which will be tweeted out at 10 'o clock tonight."
When it was suggested Mr Johnson is "on the horns of a dilemma", Ms Johnson replied: "Of course he is, and it is agonising."