BERLIN — It was a stunt but it was revealing. Lawmakers of the far-right Alternative for Germany were read quotations and then asked: Were these penned by Björn Höcke, the party’s most notorious far-right firebrand — or by Hitler?
“I can’t tell,” one said.
“I really don’t know,” another replied.
“More likely ‘Mein Kampf,’” a third guessed.
All extracts were, in fact, from Mr. Höcke’s book, describing, for example, a “longing of the German people for a historical figure who will heal the wounds in the Volk, overcome division and bring back order.”
Mr. Höcke, a history teacher turned far-right ideologue, runs the Alternative for Germany in the state of Thuringia, where the party is set to double its share of the vote to more than 20 percent in elections on Sunday, further cementing its position as a leading political force in the former Communist East.
Thuringia may be one of the smallest states in Germany, but Mr. Höcke’s national notoriety and unapologetically provocative language, packed with echoes from the 1930s, have given the poll an outsize importance.
How the Alternative for Germany, known by its German abbreviation AfD, fares in Thuringia will also help determine the sway that Mr. Höcke and his ideology will hold in the party — and its future direction, analysts say.
“These elections matter symbolically,” said Matthias Quent, an expert and author on far-right extremism and director of an institute that studies democracy and civil society in Thuringia. “Höcke’s extremist wing has been gaining influence inside the party from its eastern base.”
Nationwide, the AfD may be flatlining, Mr. Quent said. But, he added, “it is radicalizing.”
In the six years since the AfD was founded as a national-conservative, free-market protest party against the Greek bailout and the euro, it has sharply shifted to the right. A noisy nationalism and anti-immigrant stance now define its brand.
The party seized on Chancellor Angela Merkel’s decision to welcome over a million migrants to Germany in 2015, actively fanning fears of Islamization and migrant crime. Two years later, the AfD became the first far-right party to enter Parliament since World War II. By now, it sits in every state legislature in the country.
Yet the AfD itself is deeply split. In one camp are disillusioned conservatives, often former members of Ms. Merkel’s Christian Democrats, who feel alienated by what they perceive as a shift to the left of their old party on issues like migration, same-sex marriage and climate change.
In the other are hard-line nationalists like Mr. Höcke, who use language laced with ethnic hatred and close ranks with neo-Nazis during street protests.
The ideological split is also a geographic one: The far right is more moderate in western Germany — but also less successful, trailing far behind Ms. Merkel’s conservatives and garnering less than half the support of the resurgent liberal Greens.
In the former East, meanwhile, it has become a broad-based political force embedded at the grass-roots level.
“East Germany has become a refuge for the far right, a place where you can gather your strength, logistically and mentally,” Mr. Quent said.
In the AfD’s narrative, the east is avant-garde. The west, liberal and multicultural, is already lost, he said. “The east is where Germany is still Germany and where men are still men,” Mr. Quent said.
This is where Mr. Höcke has his power base. Himself a westerner, he runs a movement inside the AfD known as the Flügel, or Wing, which has become increasingly influential in the party.
Since January, the Wing has been under observation by the domestic intelligence agency, which says there were “indications” that it is “an extremist organization.”
Thomas Haldenwang, the agency’s chief, has described Mr. Höcke as the “linchpin” of the movement, and warned this month that his concerns had only grown in recent months.
“The Wing is becoming more and more extremist,” Mr. Haldenwang told Der Spiegel.
But that assessment has not harmed the AfD’s fortunes in the east, where many leading candidates who won seats in local and regional bodies in recent months belong to the Wing.
At the annual meeting of the Wing in the Kyffhäuser hills in Mr. Höcke’s constituency, he maintains a cult status, with Höcke mugs and Höcke T-shirts, among the many paraphernalia. Traditional parties have not even bothered to put up campaign posters here before the election on Sunday, so entrenched has the Wing become.
Mr. Höcke has never been coy about his views. In 2017, at a rally in Dresden, he questioned the guiding precept of modern Germany — the country’s culpability in World War II and the Holocaust — calling on Germans to make a “180 degree” turn in the way they viewed their history.
Germans were “the only people in the world to plant a monument of shame in the heart of their capital,” he said, referring to the Holocaust memorial in Berlin.
(To his dismay, activists subsequently built a copy of one section of the Holocaust memorial to scale on the property immediately neighboring his.)
Mr. Höcke has used metaphors reminiscent of Goebbels, Hitler’s chief propagandist, saying that Germans need to be wolves rather than sheep.
He uses terminology and concepts once used by Hitler himself, including racial suicide, a “decaying state’’ and “cultural Bolshevism.”
Followers of Mr. Höcke’s Wing routinely call mainstream news media the “lying press,” another Nazi term, while Mr. Höcke himself has on occasion threatened critical journalists personally.
After being shown the clips of AfD lawmakers unable to distinguish between his words and those of Hitler, Mr. Höcke stormed out of an interview with the public broadcaster ZDF — but not until promising the interviewer “massive consequences.”
“Maybe I will one day be an interesting political personality in this country, who knows,” Mr. Höcke said.
In his book, “Never Into the Same River Twice,” he openly advocates bringing down Germany’s postwar liberal order.
“A few small corrections and little reforms won’t do, but German absolutism will be the guarantee that we will tackle this thoroughly and fundamentally,” he writes at one point.
“Human harshness and unpleasant scenes won’t always be possible to avoid,” he went on, explaining the need for what he calls “temperate brutality.”
Experts like Mr. Quent call Mr. Höcke’s ideology “pre-fascist.”
“His book reads like a 21st-century ‘Mein Kampf,’” Mr. Quent said.
The danger, said Mr. Quent, was not so much that the AfD would take power in one of Germany’s states or even join a coalition. By radicalizing, he said, that prospect was, in fact, receding further.
The real risk, Mr. Quent said, was that persistent verbal transgressions would normalize violent and racist language, push mainstream conservatives to the right and over time create an atmosphere in which the bar to real violence was lowered ever further.
Since the AfD has come onto the scene, Germany has experienced an increase in far-right violence. Last year, far-right riots on the streets of the eastern city of Chemnitz saw neo-Nazis chase foreigners and AfD lawmakers march side by side with far-right extremists.
In June this year, a regional politician who had defended Ms. Merkel’s refugee policy was shot dead by a former neo-Nazi, and this month a far-right extremist attacked a synagogue in the eastern city of Halle, leaving two dead.
“Especially personalities such as Mr. Höcke from Thuringia stoke anti-Semitism through the way they make political arguments,” said Markus Söder, the conservative governor of Bavaria. “They support such perpetrators. That cannot be accepted.”
He called for the AfD to cut ties with Mr. Höcke. It has resisted those calls before. Many believe that Mr. Höcke’s movement has already won the civil war inside the AfD.
Even his critics in the party now appear to tolerate the Wing in light of its successes in the east, even if that risks costing votes in the west, said Hajo Funke, a professor at the Free University of Berlin who studies right-wing extremism.
“There is no effective strategy of resistance against Höcke,” Mr. Funke said.
At an AfD rally in the small eastern town of Sömmerda this past week, Mr. Höcke addressed a crowd of about 100 seated at long wooden picnic tables, vowing to “set democracy straight.” Germans no longer felt free to speak their mind, he said.
At the back of the crowd, men wearing blue AfD vests demanded that the police ban two women from “disrupting” the crowd with stickers they had pasted to their sweatshirts.
The police refused, saying the women were merely exercising their freedom of speech. Their stickers read, “No Place for Nazis.”
Christopher F. Schuetze contributed reporting.