Talks yesterday ran overnight as Cameron pressed his demands for EU reforms, with several of his EU peers unhappy that he should get a special deal when they have grievances of their own.
Arriving at the EU headquarters building in Brussels, Cameron said: "I was here until five o'clock this morning working through this and we've made some progress but there is still no deal."
"As I have said, I would only do a deal if we get what Britain needs so we are going to get back in there."
He has four key demands -- the right to curb migrant social welfare benefits, safeguards for non-euro countries against greater eurozone integration, an opt-out from ever "closer union" and measures to boost the EU's competitive standing.
Some member states, most notably Germany, agree with many of his reforms but others such as France and Belgium baulk at Britain having any sort of veto over those who want to press ahead with increased EU convergence.