The European Union and Turkey will attempt Friday to agree a contentious new plan to stem migration flows to Europe, in talks that German Chancellor Angela Merkel predicted would be "not entirely easy."
The plan is the EU's latest effort to end a surge of migrants and asylum seekers that saw more than 1 million people reach European shores last year. Most crossed the Aegean Sea from Turkey to Greece, aiming to then move on to wealthy northern states.
The EU wants to recruit Ankara's help in dissuading migrants from crossing the Aegean and instead having them wait to be resettled in an orderly fashion out of Turkey.
In exchange for its help, Ankara is seeking further refugee aid, as well as progress on visa-free access to the bloc for its citizens and on EU membership for the country.
EU leaders late Thursday put the finishing touches to their negotiating position, after eight hours of summit talks in Brussels.
EU President Donald Tusk will kick off negotiations on Friday at 8:30 am (0730 GMT) with Turkish Prime Minister Ahmet Davutoglu. They are expected to be joined by European Commission President Jean-Claude Juncker and Dutch Prime Minister Mark Rutte, whose country holds the EU's rotating presidency.
This could be followed by more negotiations involving all of the EU's 28 leaders if needed, an EU source said on condition of anonymity.
Tusk had said before the summit that he was "cautiously optimistic" about finalizing the new deal with Turkey this week. But Friday's talks are expected to be thorny, with several political minefields in the new plan.
"The proposed package is very complicated, will be very difficult to implement, and it is on the edge of international law," Lithuanian President Dalia Grybauskaite warned on Thursday afternoon.
"Tomorrow will be an intense and demanding day," Italian Prime Minister Matteo Renzi predicted after the first day of talks.
"We all agreed that we will focus all efforts on managing an agreement with Turkey," Merkel said. "It will certainly be not entirely easy negotiations tomorrow."
Legal concerns focus on a planned migrant swap that would see the EU send Syrian asylum seekers from Greek islands back to Turkey, as part of a bid to undercut migrant smuggling networks. Human rights advocates have called the approach inhumane and illegal.
But the EU's position was strengthened Thursday after Europe's leading rights watchdog, the Council of Europe, endorsed the approach as long as asylum applications for those arriving on Greek islands are fully processed before any returns to Turkey.
Rutte predicted that the migrant swap, which would also see the EU resettle Syrians directly from Turkey, would halt the flow of migrants across the Aegean "in three to four weeks."
Davutoglu rejected domestic criticism that the plan would turn Turkey into a giant refugee camp.
"That is out of the question," he said before leaving for Brussels late Thursday, according to the Turkish news agency Anadolu.
Turkey's demands for closer ties with the EU are also sensitive, at a time when the country has come under fire for a crackdown on opposition media.
Cyprus is considered one of the biggest potential stumbling blocks on the Turkish wish for quick progress on its long-running EU membership bid.
Cypriot President Nicos Anastasiades has insisted that Turkey first implement past obligations that would, for instance, allow Cypriot vessels to enter Turkish ports, despite the long-standing tensions between the two sides.
EU leaders are only expected to promise Turkey that they will "prepare" for the opening of new negotiating chapters. Irish Prime Minister Enda Kenny said it is "unlikely that the accession chapters will be expedited."
A Turkish quest to have its citizens get visa-free access to Europe by June is also proving sensitive. The EU is expected to continue insisting that Ankara first meet 72 prerequisite benchmarks.
"It is clear that we won't start haggling about the conditions of visa liberalization," Rutte said.
Hopes are high about the new EU-Turkey deal, but French President Francois Hollande warned early Friday against overblown expectations. Even if a deal is struck and implemented, it would not address the root causes that lead refugees to leave their homes, he said.
The real breakthrough would be for the war in Syria to end, Austrian Chancellor Werner Faymann said, adding: "Everything else is emergency measures."