Foreign Secretary William Hague has said that if any MP - Tory or otherwise - decides to take up the Private Members' Bill on an EU referendum, then the Conservative party "will get behind that".
But he added that he was not "predicting that legislation can necessarily be passed".
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.