During the coronavirus pandemic, a little-known German state lawmaker with an upbeat patter and a telegenic smile started railing on TikTok against pandemic regulations. Complaining about masks, vaccinations and other government requirements that he deemed “crazy,” the lawmaker attracted millions of viewers with his videos by using an affable tone to deliver an anti-establishment message.

Now, that lawmaker, Ulrich Siegmund, has harnessed his online popularity to come closer to power than any other far-right politician in Germany since the Nazi era ended in 1945.

Mr. Siegmund, 35, a former air freshener salesman, is the lead candidate for the Alternative for Germany party in Saxony-Anhalt, a state in eastern Germany where the party is projected to finish first in a statewide election on Sunday.

If the party, known by its German initials, AfD, wins an outright majority, Mr. Siegmund will become the first far-right politician to govern a German state since the re-establishment of the country’s democracy nearly eight decades ago. That would be a convulsive moment for Germany’s postwar political system, which was designed in the aftermath of World War II to prevent politicians deemed extremist from ever taking office.

To the political establishment in Berlin, Mr. Siegmund’s party is an outcast. The domestic intelligence agency has labeled it as “suspected extremist,” an accusation it rejects as politically motivated. The party has said that Islam is incompatible with the German Constitution and has vowed mass deportations of immigrants. Several of its leaders are close to Russia, and some have made dog whistle comments about the Nazi era, including by minimizing the Holocaust and repeating Nazi slogans.

Mr. Siegmund himself has said, in a podcast interview with Politico, that he could not “presume to judge” if the Holocaust was humanity’s worst-ever crime, “because I can’t possibly come to terms with the entirety of human history.” He also declined to condemn supporters who chanted his surname, Siegmund, in the style of the Nazi salute, “Sieg Heil.”

Still, Mr. Siegmund has won over voters in Saxony-Anhalt, experts say, through his ability to present the party’s hard-line policies in a more approachable and optimistic tone than many of his AfD colleagues, without distancing himself from extremists. In addition to deporting immigrants, the party has proposed cutting funding for public broadcasters, banning gay pride flags in schools and teaching more Russian, as well as tax breaks for large families and free child care.

“I can provide motivation, create a sense of optimism and get things moving forward again,” Mr. Siegmund said in an interview with The New York Times this year. (He declined more recent interview requests.)

That affability has made him more acceptable to voters beyond his hard-right base, said Prof. Steffen Mau, a prominent sociologist at Humboldt University of Berlin.

“He’s a canvas onto which people can project some kind of promise for the future,” Professor Mau said.

Many mainstream politicians, who have said Mr. Siegmund and the AfD are dangerous, also call his proposals unrealistic. “Whenever the topic turns to substance, when people actually ask how you intend to move our country forward economically, you’re nowhere to be found,” Sven Schulze, the incumbent governor of Saxony-Anhalt, said to Mr. Siegmund during a televised debate last month.

An August cover story in Germany’s premier newsmagazine, Der Spiegel, called him “the most dangerous man in Germany,” partly because his sunny disposition makes his party’s hard-line goals more palatable to some voters. Mr. Siegmund’s followers took it as a badge of honor and, during campaign stops, asked him to sign copies of the edition.

Mr. Siegmund is “so approachable and charming,” said Wolfram Adler, 67, a retired train driver who attended one of those rallies.

From Air Fresheners to Politics

Born in 1990, weeks after the reunification of East and West Germany, Mr. Siegmund was raised in the picturesque medieval town of Tangermünde, in eastern Germany.

Growing up in the east, he came of age amid increasing resentment about how reunification played out for his home region. The east’s economy, employment rates and population ebbed after 1990, leading many East Germans to feel excluded in the new Germany. It was a sense of grievance on which the AfD would later capitalize, particularly in Saxony-Anhalt where the unemployment rate of roughly 8 percent is well above the national average.

In his 20s, Mr. Siegmund worked as an account manager at a health care provider before starting his own business in Berlin selling room deodorizers.

He joined the Christian Democratic Union, a mainstream conservative party that currently leads the national coalition government.

But he soon grew tired of the party’s rigid leadership structures, he has said in past interviews with the news media, and joined the AfD in 2014. He was drawn to the AfD, he said, because the party stood against what he perceived as the highhanded policies of the national government in Berlin.

The AfD was founded in opposition to Germany’s adoption of the euro. After it shifted to an anti-immigrant message, Mr. Siegmund ran on the party’s slate for the statehouse in 2016. He won a seat as the party netted 24 percent of the state vote, profiting from growing concerns about Germany’s decision to welcome roughly a million refugees during the European migrant crisis. He also served on his local council alongside his father and brother.

He rose to national fame in 2021 with his personable videos about pandemic restrictions, helping to project both the party and himself as the voice of voters who felt disenfranchised by mainstream parties.

Now, Mr. Siegmund has more than 850,000 followers on TikTok, an astronomical number for any German politician, giving him a platform that helped to amplify his stump speeches on the campaign trail this summer.

When speaking to sizable crowds, he has often filmed the scene on his phone, turning the camera toward the crowds to show viewers how big they were.

“When you see all of Siegmund’s campaign appearances, it becomes perfectly clear: They’re not primarily intended for the live audience, they’re primarily for the internet,” said Paula Diehl, a professor who studies populist leaders at Kiel University.

His preppy shirts and his trademark tuft of graying hair have made him instantly recognizable in Tangermünde, his hometown of 10,000 residents. During the Times interview this year, passers-by repeatedly greeted him, wished him luck or smiled.

Throughout the conversation, he combined a measured, even tolerant tone with a hard-line, exclusionary message.

He said that he did not blame immigrants for coming to Germany — before, seconds later, vowing to make their lives in his state “very uncomfortable.”

Combining Nostalgia With Optimism

The backgrounds of his campaign team also highlight his contradictions. The production company behind Mr. Siegmund’s genial campaign videos is led by a far-right activist with the Identitarians, a movement that German intelligence has accused of extremism. Mr. Siegmund’s spokesman was once part of a banned extremist group inspired by the Hitler Youth.

Mr. Siegmund did not reply to requests for comment about these links. In interviews with other outlets, he dismissed their relevance.

Mr. Siegmund, said Professor Diehl, “pretends to engage in an inclusive discourse and then immediately shatters it.”

Part of his strategy has been to tap into nostalgia for East Germany among some residents, even though he was born after it collapsed. Though many remember Communism as a dictatorship, some recall it as a time of full employment and stability.

One campaign event featured a comedian who sang the East German national anthem — an act so contentious, because it appeared to validate an authoritarian regime, that even some AfD politicians distanced themselves from it.

At some events, Mr. Siegmund rode through the countryside on a Simson, an anemic two-stroke East German motorcycle that has long been associated with life during Communism. His machine was painted baby blue to match the AfD’s colors.

At other times, he has sought to look forward instead of back. Tapping into widespread disenchantment with high unemployment and living costs, he has painted a picture of a better, if ill-defined, future under AfD leadership.

“Things are going downhill everywhere, and that’s a bad and demotivating place to start,” he said in the Times interview. “I want things to start moving uphill,” he said.

Critics say he is simply selling false hope, pointing to his past life as a salesman.

“I discovered my strength in sales early on,” Mr. Siegmund told a business magazine in 2014. “I love to sell.”