Boris Johnson has shown a little bit more leg to Conservative eurosceptics by declaring there is an "attractive future" for Britain outside of the European Union.
Speaking to LBC radio on Wednesday morning, the London mayor said he had yet to make up his mind on Brexit, but hinted David Cameron would need to tackle immigration in order to win his backing for continued membership.
"I will see what happen with the negotiations and I am obviously a massive supporter of what the prime minister is trying to do,” he said.
"I think the penalties for getting out of the EU now are lower than they have been for a very long time. There’re is an attractive future, we should be thinking about it."
Boris dismissed the suggestion he could lead the 'Out' campaign. "I think it would be fatal for any campaign for it to be led by me," he said. "I am going to see what the outcome of the negations [are]."
He added: "I think actually he best thing for the campaign for both staying and for getting out of the EU would be if it were not dominated by political voices but had serious business people on either side lining up to make their view."
Boris said "in an ideal world" he would want to stay in a reformed EU. But indicated he would need to see fundamental changes to the free movement of people policy if he were to be persuaded.
"I don't think it's currently working with the rest of the EU," he said. "My own view is we can't endlessly continue with that arrangement."
Asked by presenter Nick Ferrari if he would advocate Brexit if changes to the free movement of people were not secured, Boris said: "I certainly think it’s something we need."
The free movement of people within the EU is one of the bloc's core principles. It is seen as incredibly difficult for Cameron to persuade other European leaders, including German chancellor Angela Merkel, to give ground.
Last night, eurosceptic peers turned on the government’s EU renegotiation tactics, with even George Osborne’s father-in-law saying freedom of movement is "crumbling before our eyes".
Last month, Boris beefed up his eurosceptic credentials when he said the cost of leaving the EU was now "lower then ever". He made the comment the same day as the launch of the official 'In' campaign.
As one of British politics' most recognisable figures, Boris has been courted by both sides. Nigel Farage has said it would be "good news" for the 'Out' campaign if the mayor decided to oppose continued membership. "We might just get him," he told Sky News in October.