Led by one of its most radical figures, Björn Höcke, the anti-immigrant, anti-Muslim Alternative for Germany party doubled its score from the previous election in 2014 to 23.4 percent in the ex-communist region, knocking Chancellor Angela Merkel's CDU party off second spot.

READ ALSO: AfD surges to second place in Thuringia state elections

The head of the Central Council of Jews in Germany, Josef Schuster, said the AfD's success could no longer be dismissed merely as “protest votes” because there was no denying the hard-right extremist ideology of Thuringia's AfD branch.

“Anyone who voted for the AfD on Sunday shares responsibility for the gradual undermining of the foundations of our democracy,” Schuster said, adding that the AfD had lured voters “with cheap racist propaganda”.

Charlotte Knobloch, a Holocaust survivor who heads Munich's Jewish community, said the fact that the party was able to garner such a strong score, shows “something fundamental has gone off the rails in our political system”.

She warned that “the erosion of democratic culture is continuing”, saying that voters who picked the AfD have “backed a party that has for years prepared the ground for exclusion and violence of the far-right”.

Christoph Heubner, deputy president of the International Auschwitz Committee, which represents survivors of the Nazi death camp, also voiced fears over the trend.

“For survivors of German concentration camps, this strong increase in votes for the AfD is a new terrifying sign that raises fear of a further consolidation of right-wing extremist trends and attitudes in Germany,” he said.

The AfD's strong result came despite widespread criticism after an October 9th attack in the eastern city of Halle, where a suspected neo-Nazi gunman tried
and failed to storm a synagogue and then shot dead two people outside.

READ ALSO: What we know about the synagogue shooting in Halle

After the bloody attack, the commissioner for combatting anti-Semitism, Felix Klein, like many other critics, argued that the AfD had trafficked in incendiary anti-Jewish sentiment.

The AfD's local leader in Thuringia, Höcke, in particular had been heavily criticised over his radical speeches, and political figures had urged the far-right party's bosses to cut him loose.

The 47-year-old had labelled Berlin's Holocaust memorial a “monument of shame” and called for a “180-degree shift” in Germany's culture of remembrance of the crimes against humanity committed by the Nazi regime.