The chief of Germany's Social Democratic Party (SPD) wants affirmation from Chancellor Angela Merkel's conservative bloc that their coalition can continue its work amid a rift over migration policy that threatens the future of the German government.
"The CDU and the CSU have paralysed each other, Germany and half of Europe for weeks," SPD chief Andrea Nahles told the Sunday edition of Germany's popular Bild newspaper. "On Tuesday we need to have a straight talk about this."
The heads of the Merkel's Christian Democratic Union (CDU), its Bavarian sister party, the Christian Social Union (CSU), and the SPD are due to meet each other on Tuesday for the first session of the coalition committee since Germany's parliamentary elections in September.
The talks are expected to focus not only on the conservatives' quarrel over migration policy, but also on Merkel's agreement on European reforms with French President Emmanuel Macron.
"What I want to know from the CDU, and especially from the CSU: Are they still capable of carrying out constructive work in the government, and do they even want to do so?" Nahles said.
Germany, like several other EU countries, has struggled to reach political consensus on its migration policy as voters increasingly show support for a reduction in the number of incoming migrants and asylum seekers.
The question unleashed a power struggle between Merkel and Horst Seehofer, her CSU-member interior minister, who has threatened to order German border authorities to turn away asylum seekers who have already registered in another country.
The chancellor has rejected this go-it-alone approach and instead wants a European solution with bilateral agreements for the return of already-registered refugees.
Seehofer has given Merkel until the end of the month to find such a solution - a deadline that coincides with an EU summit in Brussels on June 28-29.
Seehofer's vow to defy Merkel with border rejections could force the chancellor's hand in removing him from office or lead to a breakdown in Germany's coalition agreement with the centre-left SPD.
Migration policy will feature prominently at the EU summit, and in preparation, Germany and 15 other EU member states have sent representatives to the Belgian capital on Sunday to map out their course on asylum policy.
In the meantime, the bitter dispute over asylum seekers between Germany's conservative parties seems to have hit their polling prospects and benefited the far-right.
Combined support for Merkel's CDU and the Bavaria-only CSU slipped two percentage points to 31 per cent, according to Bild newspaper's weekly Emnid poll. Voter support for the SPD remained unchanged at 18 per cent.
The far-right anti-migration Alternative for Germany (AfD) gained one point to reach 16 per cent, representing its best performance in an Emnid Sunday poll to date.
A total of 2,336 German voters were surveyed for Sunday's poll between June 14 and 20.
