EU leaders will make another attempt Monday to stem a migration surge that is testing their unity and principles, with hopes high that neighbouring Turkey will shoulder more of the burden.
Nearly 140,000 migrants and asylum seekers have reached Europe's shores since the beginning of the year, following more than 1 million arrivals in 2015. Almost half of them are fleeing war-ravaged Syria, according to the United Nations' refugee agency, UNHCR.
The surge has created tensions in the European Union and put at risk its most notable achievements, such as the Schengen free-travel zone and the concept of solidarity between member states.
EU President Donald Tusk, nevertheless, showed himself carefully optimistic ahead of the 28 leader's summit, which he will chair.
"For the first time since the beginning of the migration crisis, I can see a European consensus emerging," he wrote to the leaders. "It is a consensus around a comprehensive strategy that, if loyally implemented, can help stem the flows and tackle the crisis."
The EU leaders will be joined for part of their talks by Turkish Prime Minister Ahmet Davutoglu, whose country has become the main launch pad for migrants trying to reach Europe. German Chancellor Angela Merkel had been due to hold preparatory talks with Davutoglu in Brussels on Sunday evening.
The EU wants Ankara to hold back asylum seekers and is now also pushing for Turkey to take back economic migrants who have arrived in Greece, but do not qualify for asylum.
Tusk visited Davutoglu in Ankara before the summit and said they both believe that migration flows can be reduced "through large-scale and rapid return from Greece of all migrants not in need of international protection."
"The political will is there, but it poses a logistical challenge, in which we have to support Greece," Tusk wrote to the leaders.
Their meeting with Davutoglu will be overshadowed, however, by the Turkish government's takeover of the Zaman opposition newspaper. Turkey must respect freedom of the media, particularly as an EU membership candidate, the office of EU foreign policy chief Federica Mogherini warned at the weekend.
The Brussels summit is also likely to be dominated by a developing humanitarian crisis in Greece, where thousands of migrants have become stranded after countries further north restricted passage through their borders.
That pressure comes on top of economic woes that have led to three international bailouts for Greece since 2010. Greek Finance Minister Euclid Tsakalotos last week vowed to proceed with bailout-required reforms, but also warned that the situation in Greece will become "intolerable" if a European solution on migration is not found.
The leaders are set to pledge support to Greece at their summit, but also declare that the so-called Western Balkans migration route - stretching from Greece through the Balkans and on to wealthy northern European countries such as Germany or Sweden - is "closed," according to a draft of their joint statement seen by dpa.
"The EU will stand by Greece in this difficult moment and will do its utmost to help manage the situation that has arisen as a consequence of this development," it says. "This is a collective EU responsibility."
The German refugee aid organization Pro Asyl called Saturday on EU countries to create "a way out" for those stranded in Greece.
"The needy cannot be coolly taken advantage of to deter others," Pro Asyl head Guenter Burkhardt said. "Compassion of any kind seems to be getting lost."