BERLIN — The solution to the biggest challenge facing German parties in coalition talks — whether to cap the number of refugees allowed into the country — lies with the European Union, according to the most senior German lawmaker in the European Parliament.

“All coalition parties — the Greens, the liberals as well as the two conservative sister parties — agree that we need a European answer to the refugee question,” Manfred Weber, leader of the European People's Party in the Parliament and deputy party chief of the Christian Social Union, told POLITICO.

“We should look at what’s already on the table in Brussels, which ... could significantly contribute to the discussions [in Berlin] in the weeks to come,” he said, suggesting that the EU expand its current resettlement system of allocating refugees from outside the EU across the bloc.

On Sunday, the leaders of Chancellor Angela Merkel’s Christian Democrats (CDU) and Weber’s Christian Social Union (CSU) — which are sister parties — will meet in Berlin for closed-door talks to lay the groundwork for coalition negotiations with the Free Democrats (FDP) and the Greens later in the fall.

It won't be easy as Merkel will have to deal with the conflicting interests of the business-friendly FDP, the environmentalist Greens, her own center-right CDU and the hard-line demands of the CSU.

Over the past couple of months, the chancellor’s Bavarian allies — who are often her harshest critics — have repeatedly stressed that they will insist on an upper limit on the number of refugees Germany accepts each year. That's something Merkel vehemently opposes, as do the leaders of the other two parties touted to be in her governing "Jamaica" coalition.

"It's normal that as individual parties we establish individual priorities," Weber said Thursday. "But we also have to find solutions."

In what he described as a bridge "to bring the potential coalition parties together," Weber suggested solving the controversial issue of an upper limit on refugees — Obergrenze in German — by boosting European cooperation.

As well as tightening up security at the bloc's external borders and more cooperation with Africa, he said the EU needed "to apply a refugee policy similar to Canada, working with fixed limits."

He added that "this would build a bridge toward limiting [the number of refugees], which is demanded by almost everyone in Europe.”

No constitutional change

Last month, Merkel's CDU won the election but suffered heavy losses to the far-right Alternative for Germany (AfD). Immediately after the results were announced, Merkel's current coalition partner, the Social Democrats, said they did not want to spend another term as her junior partner, leaving the three-way coalition between her conservative bloc, the FDP and the Greens as the only viable option.

Since then, few issues have caused as much controversy as the Bavarian demand for an upper limit on refugees.

The other parties not only question its feasibility but also say it would run counter to Germany’s laws on asylum, as set down in the constitution — known as the Basic Law.

Weber said that for his suggestion of solving the refugee issue at the EU level "we would not need to change the German Basic Law," adding that the "right to asylum" applied only to those seeking protection because of political persecution in their own country — which is only a small fraction of those applying for asylum in Germany.

“The right to asylum is excluded from this entire debate,” he said, calling it "one of the great fundamental laws that are not up for discussion and where there cannot be an upper limit.”

“Besides ... there is the [separate] question of refugees — for example those fleeing the war in Syria — who are granted protection under the law of the Geneva Convention,” Weber said, adding that "there are already some EU rules, and now we need to develop this further.”