An inter-EU fight on migration policy broke out Tuesday, forcing European Council President Donald Tusk to alter his plans for this week's leaders' summit.

The fight, in which Migration Commissioner Dimitris Avramopoulos called Tusk's plans for relocating refugees "anti-European," highlights the continuing divide over how to deal with the aftermath of the 2015 migration crisis.

Officials and EU member countries remain divided over how to replace the bloc's the "Dublin regulation" — under which the country in which an asylum seeker arrives is responsible for them — and whether to introduce a mandatory or a voluntary relocation system for those entitled to international protection.

Tusk, in an effort to push discussion onto the agenda of this week's European Council summit, sent a note to EU leaders in which he declared: "Only member states are able to tackle the migration crisis effectively. The EU’s role is to offer its full support in all possible ways," adding that "the issue of mandatory quotas has proven to be highly divisive and the approach has turned out to be ineffective."

Several countries reacted furiously to Tusk's language, and his suggestion that the primary responsibility should fall on frontline countries such as Italy, Spain and Greece. Leaders who paid a high political price for supporting the controversial relocation plan, including German Chancellor Angela Merkel, were also deeply irritated.

“The paper prepared by President Tusk is unacceptable. It is anti-European" — Dimitris Avramopoulos

The issue was discussed at length at a meeting of government officials on Monday, with Italy, Germany and Sweden critical of the Tusk letter, two diplomats said.

Speaking on behalf of the Commission at a news conference at the European Parliament in Strasbourg, Avramopoulos punched back hard.

“My position is very clear,” Avramopoulos told reporters. “The paper prepared by President Tusk is unacceptable. It is anti-European, and it ignores all the work we have done during the past years and we’ve done this work together.”

"This paper is undermining one of the main pillars of the European project, the principle of solidarity," a visibly angry Avramopoulos added. "Europe without solidarity cannot exist.

"Our success in managing migration cannot be attributed to individual member states. These are European successes that are the results ... of our joint actions, of our joint efforts, of the European Union institutions, its agencies and all members states."

European Council officials said the controversy was unavoidable, and in many ways healthy, because Tusk was pushing leaders to debate a contentious issue over dinner at the summit on Thursday, without the pressure of adopting a new migration policy.

"They need to sit down, look each other in the eyes and discuss what are we going to do about this, because it's not going to go away," one Council official said. "The point of having these political discussions without conclusions is exactly to confront the difficult issues. The intention is that that eventually will help unblock the deadlocks in the Council. That's the very idea of the leaders' agenda."

Softer language

Still, by late afternoon Tusk had issued a revised note for the summit, with a decidedly more upbeat description of the EU's efforts, that seemed to sharply alter course by calling for the EU institutions to work in partnership with individual countries to address migration issues.

"The EU can only tackle illegal migration effectively with the full involvement of Member States and by the coordinated use of EU and Member States means and instruments," he wrote. "No Member State can deal with this common challenge on its own, but decisive action by lead Member States, backed by the EU and assistance from other Member States, has proven to be effective."

However, the new paper still declared the mandatory relocation system a failure. "The issue of mandatory quotas has proven to be highly divisive and the approach has turned out to be ineffective," Tusk wrote.

Indeed, the program was so controversial that Hungary and Slovakia, later joined by Poland, challenged it in court, unsuccessfully. Budapest and Warsaw in particular, have remained defiant.

Commission officials, including Avramopoulos, disputed Tusk's assessment, noting that more than 32,000 refugees, or more than 90 percent of those eligible and willing to participate, had been successfully relocated. Council officials countered that during the same time period more than 1.5 million asylum seekers had arrived in Europe. The mandatory relocation scheme, proposed by the Commission and approved by the Council in 2015, was supposed to relocate about 160,000 refugees.

"Is it ineffective? Yes: relocation does not solve the migration crisis, it does not reduce the number of illegal migrants arriving in Europe," a Council official said, speaking on condition of anonymity.

MEP backlash

While the Council views migration policy as an issue ultimately to be decided by leaders, the Commission and Parliament expect to exert substantial influence on new EU migration plans.

Tusk’s suggestion that mandatory quotas should be dropped threatens to scupper any chance of a deal with the Parliament, which has equal say over the EU’s asylum policy.

“It’s shocking to me,” said Cecilia Wikström, a Swedish MEP who has led discussions in the Parliament on the Dublin system, adding she was “absolutely convinced” that there was enough support among EU countries for mandatory quotas even without the backing of the Visegrad Four — Hungary, Slovakia, Poland and the Czech Republic.

“We are never ever going to sign off on a proposal that does not change the reality because the reality is that our frontline member states are being left alone completely," Wikstrom said. In a jab at Tusk, a former prime minister of Poland, she added: “I wonder at this moment if Donald Tusk is acting as the president of the Visegrad Four or as the president of the Council when it comes to the reform of Dublin ... He is ruining the process by this kind of initiative."

MEPs last month voted by a big majority for an overhaul of the asylum regime that in some respects goes further than what the Commission proposed in 2016.

“This is a very good example of very bad European leadership" — Cecilia Wikström, Swedish MEP

The Parliament's position includes a mandatory allocation system that would apply at all times, not just when thresholds are breached as suggested by the Commission, and would oblige countries to take a set number of asylum seekers based on ratio calculated on the basis of GDP and population size. If a country refuses to participate in the system, MEPs want that country to lose access to EU funds.

Frontier countries like Italy also reacted angrily to Tusk's paper, even though he also proposed major new funding in the EU budget to provide more consistent financial support.

If Tusk's goal was to stir controversy, he succeeded. If his goal was to broker a compromise, it seems a tough road lies ahead.

“This is a very good example of very bad European leadership," Wikström said. "This is one of the worst examples of European leadership I have seen in recent years."