The far-right AfD party suffered a narrow electoral defeat on Sunday after huge protests swept across Germany against the anti-immigration group over revelations of debates about mass expulsions of immigrants.
A candidate from the mainstream center-right CDU won a slim victory over an AfD challenger in a run-off in eastern Thuringia for a district administrator post.
Over a million people have marched in recent days in cities from Hamburg to Dresden to Stuttgart in protest at the Alternative for Germany party and hundreds of thousands poured into the streets again on Saturday and Sunday.
The wave of mobilisation was sparked by a January 10 report by investigative outlet Correctiv, which revealed that AfD members had discussed the expulsion of immigrants and "non-assimilated citizens" at a Potsdam meeting with extremists.
Sunday's run-off vote in eastern Thuringia for a district administrator post was the first election since the outrage over the meeting.
After a first round vote in which the AfD's Uwe Thrum topped the polls in the Saale-Orla district, he garnered 47.6 percent in the deciding round against 52.4 percent for CDU candidate Christian Herrgott.
Both the CDU and the centre-left SPD heaved a sigh of relief at the result.
The leader of the CDU's Thuringia branch Mario Voigt thanked voters for joining hands to "beat the purported Alternative", while his SPD counterpart Georg Maier said the large voter turnout and mobilisation of the civil society had led to the "very important result".
The AfD had been hoping to notch up another victory after having secured its first district administrator position last June, also in Thuringia, and its first town mayor in July in neighbouring Saxony-Anhalt.
Nationwide opinion polls put the AfD in second place after the conservatives, and well above Chancellor Olaf Scholz's Social Democrats.
A first poll since the protests showed support for the anti-immigration party slipping 1.5 percentage points.
But the far-right party still tops surveys in three eastern states which are due to hold regional elections in September, even though local branches of the party in two of them -- Saxony and Thuringia -- have been classified as a "confirmed" extremist organisation by Germany's domestic intelligence agency.
The classification gives the agency more powers to monitor the branches, and had been accorded because of the AfD's efforts to undermine democracy and for its anti-immigrant rhetoric.
The AfD also said that it has gained 1,900 new members since January 10, when the Correctiv report was published.
In his regular video address released Saturday, Scholz for the second week in a row urged the population to stand up against extremists.
"'Never again' is not only directed at the state. 'Never again' requires everyone's vigilance. Our democracy is not God-given, it is man-made. It is strong when we support it. It needs us when it is attacked," he said.
At a weekend anti-Afd protest in Stuttgart, 56-year-old Wolfgang Nagel said that in many European countries "people are looking to turn back the clock and politicians are adopting an inward-looking discourse, focusing on their own nation and their own people."
Margrit Walter, 60, speaking at the same demonstration, said she was there to make a stand for her grandchildren.
"I don't want us to live in a world of Nazis. It's important to rise up against the extreme right."
