European Union leaders will grapple Thursday with one of the most divisive issues ever to face the 28-nation bloc; how to collectively share responsibility for the tens of thousands of people arriving on Europe's southern shores in search of a better life.
Ahead of an EU summit in Brussels, fresh tensions have surfaced over the perceived need for national refugee quotas. So far, solidarity with front-line nations Greece and Italy, where the refugees land, has been limited. A mandatory quota scheme was opposed mainly by eastern European nations — the Czech Republic, Hungary, Poland and Slovakia.
For Europe, the political crisis over migrants is existential, despite the fact that migrant arrivals have dropped dramatically this year.
As hundreds of thousands of Syrian refugees trekked northward from Greece in 2015, some EU nations erected fences, launched police crackdowns and closed borders, forcing migrants onto their neighbors. ID checks were reintroduced in parts of Europe's passport-free travel area, hampering trade, business and tourism.
That fueled anti-immigrant parties and the far-right made significant political inroads.
"The migration crisis was a kind of character test for the EU," Roderick Parkes, senior analyst at the EU's Institute for Security Studies, wrote Wednesday.
It has tested the EU's "capacity to lead in the field of refugee reception, to seize the economic opportunities of immigration and to share the burden borne by Turkey, Lebanon or Kenya by resettling refugees. And the EU failed the test, on all counts," he wrote.
At the center of Europe's migrant malaise are refugee quotas. In response to the arrival of more than 1 million migrants in 2015, EU nations voted by a large majority to share 160,000 of those fleeing conflict or persecution to help ease the burden on overwhelmed Greece and Italy.
Hungary challenged the quotas at Europe's top court but lost.
In an effort to clear the air, EU Council President Donald Tusk, who will chair the two-day summit in Brussels, has put the issue at the top of the agenda. But in branding the scheme ineffective, he has angered Europe's top migration official and lawmakers involved in drawing it up.
"The issue of mandatory quotas has proven to be highly divisive and the approach has received disproportionate attention in light of its impact on the ground; in this sense it has turned out to be ineffective," Tusk wrote to the EU leaders.
But EU Migration Commissioner Dimitris Avramopoulos slammed the note as "unacceptable. It is anti-European and it denies, it ignores, all the work we have done during the past years."
"This paper is undermining one of the main pillars of the European project; the principle of solidarity. Europe without solidarity cannot exist," he said. "It is a duty — moral and legal — to protect refugees."
Greens lawmaker Ska Keller said "Tusk is undermining the prospects of a solidarity-based refugee policy in Europe" and that "without a fair redistribution of refugees, European asylum policy will remain vulnerable to crisis."
The European Commission says 32,000 people from the asylum scheme have found homes. But that figure — less than a quarter of the original target — masks the legal challenges, abuses and suffering as thousands of migrants and refugees have languished in the Greek islands.
The main reason for the drop in migrant numbers is the EU's agreement with Turkey, which saw the bloc mobilize its financial might to convince Ankara to stop Syrian refugees from crossing the sea to nearby Greece and to take back thousands already there.
Spurred by that success, the EU is leveraging its considerable development aid as it draws up other outsourcing arrangements, mostly with Libya's poor neighbors to stop Africans unlikely to qualify for asylum from heading there to take treacherous sea journeys to Italy.
Tusk wants Thursday's summit discussions to promote mutual understanding about the migration challenges that the EU's neighbors face. He also wants the leaders to endorse plans to make migration a part of the EU's long-term budget, rather than rely on ad-hoc contributions.
No concrete decisions will be made Thursday. The future of mandatory refugee quotas for nations should be made clearer next June.
"It is important to look at what has — and what has not — worked over the past two years, and draw the necessary lessons," Tusk wrote. "The migration challenge is here to stay."