EU president Donald Tusk said he will unveil a proposal for a deal to change Britain's membership of the bloc after "progress" in talks that followed a meeting with Prime Minister David Cameron.
"Tomorrow around noon (1100 GMT) I will table proposal for a new settlement for #UKinEU. Good progress last 24 hours but still outstanding issues," Tusk wrote on Twitter.
Former Polish premier Tusk and Cameron had set a 24-hour deadline for diplomats to thrash out a draft accord after their talks over dinner in London broke down yesterday night without any agreement.
The proposal will then go to all 28 European Union member states to try to reach a deal on Britain's demands at a summit on February 18.
That would in turn pave the way for Cameron to hold his promised referendum on Britain's EU membership in June, his preferred date.
London's bid to transform its membership of the EU has sparked turmoil, coming as the grouping struggles with the biggest influx of migrants since World War II and the fallout from the eurozone debt crisis.
Cameron's spokesman had earlier warned that there was more work to do before any agreement.
"There is more hard work to be done," the spokesman told reporters in London. "We are making progress but there's more work to do in all four areas -- more work in some areas than others."
The four demands include safeguarding EU countries like Britain that are not part of the euro single currency, ensuring greater EU economic competitiveness, opting out of the goal of ever closer union and restricting access to benefits for EU workers in Britain.
