BRUSSELS (AP) — Four European Union countries that hundreds of thousands of unauthorized migrants have entered over the past five years have expressed concern that new proposals to revamp the EU’s asylum system will continue to leave them to cope with the challenge alone.

Greece, Italy, Malta and Spain said in a joint paper that mandatory quotas for sharing out people who qualify for refugee status among the 27 EU countries must be pursued. Austria, the Czech Republic, Hungary, Poland and Slovakia, among others, reject such a move.

The standoff could further delay the long-awaited asylum reform plans.

“The front-line member states cannot face the migratory pressure on the whole European Union,” the four countries said in a text sent to the European Commission, which drew up the asylum plans, the EU Council representing member countries and Germany, which holds the bloc’s presidency.

The entry in 2015 of well over 1 million migrants, mostly people fleeing conflict in Syria, sounded the death knell for the EU’s asylum system, and sparked a deep political crisis that continues to echo even though entries have dropped to a relative trickle.

The row over who should take responsibility for people when they arrive and how much other EU countries should assist has helped fuel public support for far-right parties across the bloc. Populist governments in Hungary and Poland, notably, challenged a previous system of migrant quotas at Europe’s top court.

In the text, seen by The Associated Press, Greece, Italy, Malta and Spain argue that their responsibilities as countries where most unauthorized migrants arrive across the Mediterranean Sea are strict and clear in the “New Pact for Migration and Asylum,” but that the duties of their EU partners are not.

“The solidarity mechanism remains complex and vague,” the four countries said.

“The notion of mandatory relocation should remain and be pursued as the main solidarity tool,” the text continued.

Under the reform plans, migrants arriving at Europe’s outside borders without permission to enter would be screened within five days. They would then enter an asylum procedure or be deported, both within 12 weeks. People could be held in detention and would not be deemed to have officially entered the EU.

EU countries would then face two choices: take in some of the refugees or provide other material and logistical support; or if they are not willing to do that, they could take charge of deporting people whose applications are refused. Mandatory refugee quotas have been abandoned.

In recent years, only about a third of all people ordered to be sent home were actually deported.

Asked Thursday about the issues raised by Greece, Italy, Malta and Spain, commission spokesman Adalbert Jahnz welcomed their acknowledgement that the reform plan is constructive and a good basis for discussions.

Jahnz said the reform plans were drawn up after “extensive consultations” and “seek to address the varied and genuine concerns of all, in the knowledge that no member state experiences migration in the same way.”

Germany has said it wants to reach a political agreement between EU countries and the European Parliament on the asylum reforms by the end of the year, in the hope that they could be officially endorsed early in 2021. But it appears likely that calendar could slip.

Migration Policy Institute Europe director Hanne Beirens said that while EU member countries “broadly agree on the idea of solidarity with flexible modalities, there is still considerable disagreement as to how (to) make this solidarity mechanism work in practice.”

The real issue, Beirens said, is that the four will have to make an “upfront investment” and they’re nervous about what kinds of solidarity they might see from EU partners that have let them down in the past.

“They would have to recruit additional staff, (invest) in infrastructure, make sure that they have sufficient accommodation for those new arrivals. Whereas the other part of the bargain — the solidarity, in the form of relocation or return sponsorship -- will come much later,” she told the AP.