Chancellor Olaf Scholz fired his finance minister on Wednesday, effectively ending his three-party ruling coalition and destabilizing his center-left government just as the election of Donald J. Trump in the United States presented Europe with new economic and security challenges.

“I would have liked to have spared you this difficult decision,” said Mr. Scholz during an impromptu news conference in the chancellery on Wednesday evening. “Especially in times like these, when uncertainty is growing,” he added.

Mr. Scholz vowed to keep governing until the end of the year and then demand a confidence vote in Parliament in January, a test he may likely fail. That would open the way to early elections, possibly in March, for only the third time since the Federal Republic was founded in 1948.

The trouble in Berlin leaves the European Union evermore rudderless at a particularly difficult time. France’s government is in a crisis after elections there this year yielded a deadlocked Parliament, and Russia has made important advances on the battlefield in Ukraine and continues to threaten Europe broadly.

Now Europe faces the possibility of a trade war with the United States and a weakening of the NATO alliance — both of which Mr. Trump has threatened — as Germany, its most populous country, becomes mired in political instability as well.

The collapse of the coalition in Germany came after the leaders of the three parties — Mr. Scholz’s Social Democrats, the left-leaning Greens and the pro-business Free Democrats — had mostly stopped talking to each other in recent weeks over widening disputes in negotiations for a new federal budget.