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.
Cameron has pledged to back a Conservative MP's EU referendum bill, as Cable labelled the move potentially 'damaging' for the country.
114 Conservative backbenchers have voted in favour of a eurosceptic motion to amend the Queen's Speech in defiance of the Prime Minister.
David Cameron has denied he has buckled under pressure from his backbench MPs over the EU debate.