The hard-right Alternative for Germany helped install a local politician as minister president in Germany's eastern state of Thuringia, triggering nationwide demonstrations and political chaos in Berlin. Constanze Stelzenmüller explains what it means. This piece originally appeared in the Financial Times .

Nice, but not necessary: It’s safe to say this is what, before this week, most Germans thought of the eastern state of Thuringia, with its sweet little towns nestled in deep, dark forests, and steady trickle of emigration. But that changed abruptly on Wednesday when the hard-right Alternative for Germany helped install a local politician as minister president, triggering nationwide demonstrations and political chaos in Berlin.

Thomas Kemmerich, of the liberal Free Democrats, owns a chain of hair salons, and likes to sport cowboy boots. In his campaign, he was careful to distance himself from the AfD. In a play on the German word for a bald pate, also used colloquially for skinheads, he used an image of his egg-like dome and the slogan “Finally a Glatze who paid attention in history class.”

The poster is an instant classic. For the head of the AfD in Thuringia is none other than Björn Höcke, the leader of the radical wing of the party, who regularly inveighs against Germany’s culture of atonement for the Holocaust as a “cult of shame.” A German court has ruled that to call him a fascist is a factual statement.

Mr. Kemmerich’s electrifying ascent is the outcome of an inconclusive state poll in October followed by three months of gridlock. The incumbent Bodo Ramelow, whose leftwing Die Linke party had come in first with 31%, had planned to remain in power at the head of a minority coalition with the Social Democrats and Greens. In yesterday’s election, Mr. Kemmerich beat him by one vote, with the support of the state chapter of Angela Merkel’s Christian Democrats — and the AfD.

Mr. Ramelow, despite the fact that his party is the successor to the former East German communists, is undogmatic, experienced and popular — so much so that even some of the more liberal CDU leaders advocated tolerating him. His victorious rival leads a party that barely scraped across the 5% vote threshold, and holds five of the legislature’s 90 seats. Related Content Essay German lessons

Crucially, the CDU, as well as its Bavarian sister party the CSU, had ruled out any form of co-operation with the AfD. Their leaders immediately demanded the resignation of the new minister president, and new elections. Paul Ziemiak, the general secretary of the CDU, called Mr. Höcke “a Nazi.”

Mr. Kemmerich, unmoved, has exhorted the CDU, the SPD and the Greens to “put ideology behind them” and work with his party. Unfortunately for him, they are not on his side, and neither is the math: The four parties together hold only 39 seats. For a legislative majority, he would need either Die Linke — or the AfD. Another election seems unavoidable.

Nor will this political earthquake stop at the borders of Thuringia. In Berlin, the FDP’s national leader Christian Lindner faces a full-on revolt in his own party after rationalizing Mr. Kemmerich’s decision to accept the AfD’s support. Alexander Graf Lambsdorff, one of the party’s deputy whips in the Bundestag, tweeted: “One doesn’t let oneself be elected by AfD fascists.”

The CDU’s embattled leader, Defense Minister Annegret Kramp-Karrenbauer, is even more embarrassed. Her strict prohibition on co-operation with the AfD is a lesson learnt from her Bavarian counterpart Markus Söder, who lost the CSU’s sacred absolute majority with an AfD-lite campaign in 2018 and has since become the hard right’s exorcist-in-chief. But the CDU’s eastern chapters, demoralized by the AfD’s recent surges, have been rattling their chains. The revolt in Thuringia threatens Ms. Kramp-Karrenbauer’s authority, and her claim to succeed Angela Merkel as chancellor.

Then there is the SPD, Ms. Merkel’s reluctant grand coalition partner. Its leaders have quelled multiple breakout attempts by the restless leftwing of the party. Now the leadership is invoking an “unforgivable breaking of the dams.”

The AfD is openly gloating over its success as kingmaker, and the disarray it has produced. Some are predicting it might come first in new elections (it came in second in 2019, with 23.4% of the vote). The German New Right’s mastermind Götz Kubitschek praised Mr. Höcke for the feat of simultaneously “seating one person in Thuringia and chopping off the legs of another chair in Berlin.” It was clear whose chair he meant.

An irony of this drama that has gone mostly unremarked is that in a region where outsiders are viewed with suspicion and western carpetbaggers are especially resented, messrs Ramelow, Kemmerich, and Höcke are all West Germans. It would be an even darker irony if this state with only 1.7 million voters brought down unified Germany’s first East German chancellor.