Boris Johnson has backed Tory backbench demands for an EU referendum bill and warned David Cameron he must make clear Britain is "ready to walk away" unless its relationship is fundamentally reformed.
But the Conservative Mayor of London also issued a stark warning to eurosceptics that quitting would expose the fact that most of the country's problems were self-inflicted.
"If we left the EU, we would end this sterile debate, and we would have to recognise that most of our problems are not caused by 'Bwussels', but by chronic British short-termism, inadequate management," he wrote in his Daily Telegraph column.
"Sloth, low skills, a culture of easy gratification and underinvestment in both human and physical capital and infrastructure" also contribute to problems at home, he added, noting that British productivity compares badly to our German neighbours.
Mayor of London Boris Johnson has said the UK needs to 'think globally' if it is to succeed and says restrictions imposed on Europe by Brussels is preventing growth.
Speaking from the Global Investment Conference in the capital he said that what he and what he thinks the Prime Minister, wants to see is a renegotiation of the rules imposed on Europe by Brussels.
He said the 'micro-climate of gloom' in the eurozone has been caused not just by the Euro but by the rules and regulations created over the past few decades by Brussels which Boris Johnson says is holding back growth.
The Mayor of London said a renegotiation is needed to 'get rid of some of that nonsense'.
"If that fails, then yes obviously we should be ready to walk away, I don't think that is as existential, as dramatic a step as it was perhaps 10 or 20 years ago." - Boris Johnson