German Chancellor Angela Merkel will meet some of her European Union peers on Sunday to try break a deadlock on migration and head off a possible clash over the bitterly-contested issue at a June 28-29 EU summit.

Merkel will be joined by French President Emmanuel Macron, as well as the leaders of Bulgaria and Austria, among others, to explore how to prevent people from moving around the bloc after they have already claimed asylum in one of the Mediterranean states of arrival.

Such secondary movements are illegal under EU law but have been widespread since immigration to Europe peaked in 2015, when more than a million refugees and migrants arrived from the Middle East and Africa.

The bloc has since been bitterly at odds over how to share out the responsibility of taking care of them.

The eastern EU states led by Poland and Hungary refuse to host some of the new arrivals to alleviate the burden on coastal Italy and Greece and the wealthy countries like Germany where people mostly want to end up.

Immigration figures are now much lower, with only 41,000 sea arrivals so far this year, according to U.N. data.

But Merkel’s coalition partner, the Christian Social Union (CSU), has said it would introduce a ban on entry to Germany for all asylum-seekers already registered in another EU state unless the June 28-29 summit agrees an EU-wide deal on sharing them out evenly.

The CSU idea is opposed by Merkel and the stand-off with the party leader and Germany’s interior minister Horst Seehofer has threatened the stability of her coalition.

It has also brought back the issue of migration to the top of the EU’s political agenda.

Sources said the leaders of Italy, Greece, Spain and Malta would also take part in the Sunday meeting, aimed at trying to prepare a deal on migration at the main summit next week.

While an agreement on relocating refugees and migrants arriving in Italy and Greece to other EU states evenly is as far away as ever, the EU is now trying to shift attention to a different area and one where all member states agree.

That means the summit is set to produce even more promises of tightening the bloc’s external borders and cooperating closely with countries from Turkey and Jordan to Libya and Niger on preventing refugees and migrants from ever reaching Europe.

The summit’s draft joint statement, seen by Reuters, has already called for more efforts to combat secondary movements.

It has also proposed looking into creating “regional disembarkation platforms” outside of the EU where asylum requests would be assessed before claimants get to Europe.

With chances for an EU deal on sharing out those who make it to Europe close to zero, sources said Germany would want the Sunday meeting to produce a commitment from states like Greece and Italy to take back asylum-seekers who make it to Germany.

Berlin would then work bilaterally with them on implementing that.

“Merkel needs to do this to help Seehofer climb down from a tree,” one senior EU diplomat said.

The German chancellor has already had backing from Macron on that after they held talks in Mesberg on Tuesday. They warned against unilateral moves – like the one proposed by Seehofer – but also stressed the need to combat secondary migration.

With political tension over migration on the rise in the EU, the results of the looming EU summit are set to make getting to Europe and winning asylum even harder in the future, something rights groups have long decried as turning the continent into a “fortress” shut off from less-privileged parts of the world.