Another key policy area where the coalition struggled to agree a position was on whether children should be banned from social media, a flagship EU-wide proposal from von der Leyen. While Merz personally backed the idea at the start of the year, he and his political allies spent more than six months struggling to land on a specific age limit to lobby for when von der Leyen was consulting with partners, according to officials and diplomats involved in the talks.

Even before the latest crisis, Merz’s domestic troubles were spilling into Brussels at the highest level. Last year, he surprised fellow EU leaders by demanding that a summit scheduled to cover geopolitics and other policy files should instead focus on saving European heavy industry from competition with the U.S. and China.

Germany lost around 124,100 industrial jobs last year, according to an analysis by EY, with the government concerned deindustrialization is helping drive support for Merz’s far-right and far-left rivals. Other capitals share his concerns, but Merz has insisted industry should top the agenda at future summits.

But even inside the chancellor's own CDU, he has struggled to achieve consensus on what to do about it. As the Commission plans a push against unfair Chinese trade practices, Merz's fellow party member and foreign minister Katherina Reiche is seen as more protective over the relationship with Beijing, and the German industrial giants like Volkswagen and BASF that trade with it.

In a speech on Thursday commemorating 36 years of German reunification — the fall of the Berlin Wall and the dissolution of communist East Germany —the country's ambassador to the EU, Thomas Ossowski, told fellow envoys and officials that "whenever we celebrate German unity, we celebrate European unity. And we need this unity [now] more than ever."

Gabriel Gavin reported from Brussels. Frida Preuß reported from Berlin. Jordyn Dahl, Eliza Gkristi and Carlo Martuscelli contributed to this report.