KHABAROVSK, Russia — Valentin Kvashnikov, a construction worker and recovering heroin addict, lives near the railway depot in a wooden shack, with a plastic trash can in the corner that serves as his toilet.
But he has risen from obscurity into a celebrity in far eastern Russia by helping to energize the antigovernment demonstrations that have gotten bigger and bolder in the past three weeks.
“It’s him!” a passing woman, Natasha Gordiyenko, said after she spotted Mr. Kvashnikov outside his house on Sunday, before unleashing a tirade of profanity against Russian officialdom.
The protests in Khabarovsk reached well into the tens of thousands over the weekend, establishing this distant city — some 4,000 miles from Moscow — as the site of the biggest popular challenge to President Vladimir V. Putin’s authority that a city in Russia’s far-flung regions has produced in his 20 years in power.
The protests have no leader and few concrete demands. But they have electrified a quiet city half a world away from the capital, turning apolitical residents into activists overnight and showing how quickly the embers of discontent over corruption, poverty and the stranglehold of Mr. Putin’s rule can ignite a conflagration.
“It’s not that there is something wrong with us,” said Elena Okhrimenko, a retired accountant, who has been protesting with homemade signs along with her husband, a retired truck driver. “We realized that there is something wrong with the country.”
The involvement of protesters from a broad cross-section of the city, an eight-hour flight from Moscow and only 15 miles from China, is a new kind of warning for the Kremlin. For years, large-scale protests have mainly been limited to Moscow and St. Petersburg, making them easy to dismiss as the work of an out-of-touch urban elite.
Yet the well of popular anger so far from the capital undercuts the Kremlin’s narrative of Mr. Putin’s Russia, which he has essentially ruled for the past two decades.
Mr. Putin won a heavily orchestrated referendum less than a month ago that rewrote the Constitution to allow him to stay in office until 2036. But many analysts have called the vote fraudulent, and while pollsters have identified rising discontent among Russians in recent years, the anger has never spilled into the streets with such force outside the nation’s biggest cities.
“For now, society doesn’t appear to be so radicalized as to storm the gates, if you will,” said Tatiana Stanovaya, a nonresident scholar at the Carnegie Moscow Center, a research organization focused on politics and policy. “But from my point of view, that is only a question of time if the authorities are not able to see what is really happening in the country.”
Mr. Kvashnikov, long struggling with poverty and grousing at the state’s injustice, turned into a bullhorn-carrying cheerleader of protesters who have marched through the city each day since July 11 in defense of their popular governor, Sergei I. Furgal, who was arrested by the federal authorities this month.
The protesters gather in Lenin Square in front of the marble-sheathed hulk of the regional government headquarters — known locally as the White House — before spilling into the road for a three-mile loop above the sprawling Amur River.
Cars honk in support, drivers offer high-fives and marveling bystanders — the ice-cream vendor, the cosmetics shop security guard, the officer in front of the railway-company building — have their phones out to record the scene.
“I never believed our people were so united,” Mr. Kvashnikov said, describing the protests.
The protests have drawn their ranks from political novices like Elena Skorodumova, a 23-year-old kindergarten teacher’s assistant. On July 9, she was scrolling through a social media page devoted to local news and pets when she saw a post about the arrest of Mr. Furgal, the governor. In a sharp blue suit, Mr. Furgal was pictured being led away by a masked Federal Security Service officer in camouflage gear, a gloved hand pressing down on the governor’s head.
Ms. Skorodumova recalls that she got goose bumps from her anger. The “only way” to support the governor, she wrote in the comments, was to “go out in the streets.”
The arrest of the governor, on suspicion of having organized murders some 15 years ago, seemed to many residents a blatant power play by the Kremlin to get rid of a regional leader seen as insufficiently loyal.
Mr. Furgal, a former scrap metal trader, defeated the incumbent, a widely disliked ally of Mr. Putin’s, in the 2018 regional election. Then Mr. Furgal won over residents with a populist style that his staff assiduously documented on Instagram.
Officially dismissed by Mr. Putin last week, Mr. Furgal had highlighted how he set aside millions of dollars for school lunches, cut his own pay and put the governor’s yacht on the market.
More calls for protest over his arrest coursed through social media, often in the coded language of invitations for a stroll or “feeding the pigeons” in the central square.
On July 11, a Saturday, Ms. Skorodumova, the teacher’s assistant, packed sanitizing wipes and a toothbrush in case she got arrested and went to Lenin Square. She had never protested before.
Mr. Kvashnikov, the construction worker, found a wellspring of people who shared his disdain for Mr. Putin and what he sees as a system that enriches the few. He has scarcely enough money to eat, he said, and had been involved in criminal groups and done time in prison in an earlier life.
“You rabid dog, why don’t you deal with what is under your own nose?” he said of Mr. Putin. “Your people are hungry. Look at how your people live.”
Mr. Kvashnikov drew the attention of the many YouTubers livestreaming the protests by his almost daily attendance, his loud chants and his readiness to defy the police. In one widely viewed video, he can be seen shouting at a police officer that the Russian Constitution guarantees freedom of assembly. The crowd next to him starts chanting “We’re the ones in charge here!”
The crowds of demonstrators have grown for three consecutive Saturdays, with some estimates putting last weekend’s crowd at more than 50,000 — a spurt of spontaneous political activism that is rare in Russia.
Alyona Panteleyeva, 22, and her mother run a cramped sewing workshop and fabric store. She said she had never been involved in politics until one of her employees suggested producing face masks that say “I Am/We Are Furgal.”
For the past week, the workshop has been producing about 50 masks a day, and Ms. Panteleyeva said she was selling them at cost over Instagram and in her store. The first person who bought one, she said, paid in cash marked with a pro-Furgal slogan; such bills are increasingly in circulation in the city, she explained.
“I am sure that the protests will continue until the citizens get what they want,” including a public trial for Mr. Furgal in Khabarovsk, rather than in Moscow, she said. “We are fighting for the truth.”
Mr. Furgal’s popularity as a regional elected official is unique, so the Khabarovsk protests are not likely to be replicated elsewhere, the social scientist Sergei Belanovsky wrote recently. But they show an increased willingness to protest in response to any number of slights.
“Given the overall unfavorable economic and social situation, the reasons to protest keep growing in number,” Mr. Belanovsky said. “The fabric of the state has thinned, and to tear it requires less and less effort.”
Mr. Putin remains in control of the country’s powerful security services, and, though in decline, his approval rating stands at 60 percent. A major question is to what extent the Kremlin will be prepared to use force to put down protests — it has done so in Moscow but not yet in Khabarovsk. At one point on Monday, a sole police officer followed the column of roughly 1,000 protesters, apparently to keep the cars at bay.
Many protesters assume that some police officers sympathize with them. Analysts also say that the Kremlin seems to be hoping the protests will fade on their own, and the state media has largely ignored them. Meanwhile, the authorities seem to be putting pressure on some activists.
Late Sunday evening in Lenin Square, videos showed Mr. Kvashnikov haranguing a man in plainclothes who he said had threatened him, then being wrestled to the ground by other people in plainclothes; he was carried by his ankles, chest and elbows to a waiting police car.
Hours later, the authorities released Mr. Kvashnikov. Waiting video bloggers were there to record his walk from the police station. Mr. Kvashnikov had already let his fans know that he was taking a break from protesting, for his family’s safety.
“Don’t be afraid and keep at it, friends,” Mr. Kvashnikov said in a video message recorded on Sunday. “Most important, don’t abandon what we started together.”
Oleg Matsnev contributed research from Moscow.