Thomas Kemmerich, a politician from the economically liberal Free Democratic Party (FDP), scored 45 votes, leapfrogging incumbent Bodo Ramelow of the Left party (die Linke) by one vote.
Ramelow has served as state premier since 2014.
The result comes despite the FDP having just five seats in the Thuringia state parliament, and has led to many accusing mainstream parties like the conservative Christian Democrats (CDU) of working with the AfD.
“This is the first time in the history of modern Germany that a state premier has been elected into office with AfD votes,” Erfurt political scientist André Brodocz told German broadcaster MDR on Wednesday.
The AfD's own candidate received zero votes, indicating the party's state legislators aligned as a bloc behind Kemmerich.
While the vote was secret, the liberal candidate must also have enjoyed support from lawmakers belonging to Chancellor Angela Merkel's conservative CDU, as well as his FDP stablemates.
In total, the opposition parties of the CDU, FDP and AfD have 48 seats in the state parliament – six more than the minority coalition.
Media were quick to describe the event as a “political earthquake”, as mainstream parties had so far refused to countenance working with anti-immigration, anti-Islam and anti-EU AfD at any level.
Addressing the local parliament in Erfurt, Kemmerich sought to assuage concerns by insisting he would stick to a pre-election pledge not to work with the AfD.
“You have in me a bitter opponent of anything that even hints at radicalism, from the right or left, or fascism,” he said, to jeers from local MPs and shouts of “Hypocrite!” and “Charlatan!”.
How did it happen?
The far-left Die Linke (the Left), scooped 31 percent of the vote in Thuringia's state election last October, marking the first time the party has come out on top in a regional vote in Germany.
But the Left, centre-left Social Democrats (SPD) and the Greens were unable to continue their majority in the Thuringia state parliament and decided to continue as a minority government.
Meanwhile, last October’s vote saw the AfD surge into second place in Thuringia with 23.4 percent. And this outcome shows how the party is using its new-found power.
Brigit Keller of The Left congratulates Thomas Kemmerich of the FDP. Photo: DPA
'Bad day for liberals'
People from across the political spectrum quickly condemned the tacit cooperation between CDU, FDP and AfD.
“Every decent liberal should be ashamed that an FDP man has been elected with votes from the AfD,” tweeted Hubertus Heil, federal labour minister from SPD.
Voices within the FDP were divided, with board member Marie-Agnes Strack-Zimmermann tweeting that the “unacceptable and unbearable” alliance made it a “bad day for me as a liberal”.
But the party's deputy leader Wolfgang Kubicki welcomed Kemmerich's election as state premier.
AfD co-leader Jörg Meuthen told the Frankfurter Allgemeine daily the vote showed there was “less distance” between the CDU, FDP and AfD than other parties, showing the movement was part of a “middle class” majority.
It would be “understandable” if the AfD demanded ministerial jobs in Kemmerich's government, he added.
As in other eastern states, the autumn 2019 election brought a surge there for the AfD.
But in light of the firewall towards the far right, incumbent state premier Ramelow was widely tipped to be reelected.
The surprise result led to anger on social media. The hashtag #Thüringen was trending on Twitter on Wednesday.
Retired German footballer Hans Serbei said it was a “sad day” for Germany.
“For the first time since the war, Nazis help a state premier into office. I'm speechless.”
Ein trauriger Tag für Deutschland. Das erste Mal seit dem Krieg helfen Nazis einem Ministerpräsidenten ins Amt. Ich bin sprachlos. #Thüringen
— Hans Sarpei (@HansSarpei) February 5, 2020
Despite the 2019 regional election robbing his coalition of absolute control in the state parliament, most observers had expected Ramelow, a popular local politician, to win a simple majority.
Talks to find a possible majority coalition, rather than continuing with his weakened alliance of Left party, social democrats (SPD) and Greens, were complicated by national politics.
Merkel's CDU, who placed third in last year's ballot after the Left and the AfD, argue both are too extreme in their positions and have a nationwide policy of not working with either party.
The dam breaking in Thuringia is all the more surprising to observers as the AfD's leader there, Björn Höcke, is one of the party's most radical figures, heading a loose movement within the party known as the “Wing”.
Björn Höcke congratulating Thomas Kemmerich. Photo: DPA
He has in the past called for a “180 degree turn” in Germany's culture of remembrance for the Holocaust and other crimes of the Nazis, which form a central pillar of the country's post-World War II political life.
Jewish leader 'horrified'
Wednesday marked a “new start for Thuringian politics,” Höcke said, adding the AfD had helped stop it becoming a “left-wing state”.
Central Council of Jews in Germany president Josef Schuster said in a statement he was “horrified” by Wednesday's vote.
“The FDP has quit the consensus among democratic parties not to work together with the AfD or to count on the far right's support,” Schuster said.
Kemmerich is only the second FDP state premier in modern German history.
Chairman of the Left Party, Bernd Riexinger, said it was 'breaking a taboo'.
Wie weit sind wir gekommen, dass die FDP einen Ministerpräsidenten #Kemmerich wählen lässt mit den Stimmen des Faschisten #Höcke und der #AfD?Das ist ein #Tabubruch, der weitreichende Folgen haben wird. Die #FDP und #CDU müssen jetzt einiges erklären.
— Bernd Riexinger (@b_riexinger) February 5, 2020
The SPD in Thuringia accused the FDP of “disregarding the will of the voters”
After the election of Kemmerich, which it supported, the Thuringian CDU has demanded separation from the AfD.
“The decisive thing now is that Kemmerich makes it clear that there is no coalition with the AfD,” CDU party and faction leader Mike Mohring said.