"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.
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.
More From This Section
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."