LUCKNOW, India — A Hindu warrior-priest has been chosen to rule India’s most populous state, and the cable news channels cannot get enough of him. Yogi, as everyone calls him, is so ascetic and incorruptible that he doesn’t use air-conditioners, they say. Yogi sleeps on a hard mattress on the floor. Yogi sometimes eats only an apple for dinner.
But the taproot of Yogi Adityanath’s popularity is in a darker, more dangerous place. As leader of a temple known for its militant Hindu supremacist tradition, he built an army of youths intent on avenging historic wrongs by Muslims, whom he has called “a crop of two-legged animals that has to be stopped.” At one rally, to a crowd shouting its approval, he cried out, “We are all preparing for religious war!”
Adityanath (pronounced Ah-DIT-ya-nath) was an astonishing choice by Narendra Modi, India’s prime minister, who came into office three years ago promising to usher India into a new age of development and economic growth, and playing down any Hindu-right agenda. But a populist drive to transform India into a “Hindu nation” has gradually drowned out Mr. Modi’s development agenda, shrinking the economic and social space for the country’s 170 million Muslims.
Few decisions in Indian politics matter more than the selection of the chief minister of Uttar Pradesh, because the post is seen as a springboard for future prime ministers. And the designation has done its work: At the age of 45, the diminutive, baby-faced Adityanath is receiving the kind of career-making attention that projects an Indian politician toward higher office.
“He is automatically on anybody’s list as a potential contender to succeed Modi,” said Sadanand Dhume, an India specialist at the American Enterprise Institute. “They have normalized someone who, three years ago, was considered too extreme to be minister of state for textiles. Everything has been normalized so quickly.”
Adityanath did not respond to repeated requests for comment for this article.
In March, when the Bharatiya Janata Party won a landslide electoral victory in Uttar Pradesh, political prognosticators expected Mr. Modi to make a safe choice — Manoj Sinha, a cabinet minister known for his diligence and loyalty to the party. On the morning of the announcement, an honor guard had been arranged outside his village.
But by midmorning, it was clear that something unusual was going on. A chartered flight had been sent to pick up Adityanath and bring him to Delhi for a meeting with Amit Shah, the party president. At 6 p.m. Adityanath’s appointment was announced, sending a ripple of shock through India’s political class.
They were shocked because Adityanath is a radical, but also because he is ambitious, even rebellious. As recently as January, he walked out of the B.J.P.’s executive meeting, reportedly because he was not allowed to speak. Mr. Modi, for his part, is not known to have much tolerance for rivals.
The appointment “invests a certain amount of power in Yogi Adityanath that cannot be easily taken away,” said Ashutosh Varshney, a professor of political science and international studies at Brown University.
“Modi has been either unwilling to stop his rise, or unable to stop his rise,” he said.
As a young man, Adityanath’s passion was politics, not religion. One of seven children born to a forest ranger in a mountain area famous for producing tough, disciplined military men, Adityanath, born Ajay Singh Bisht, found his vocation in college as an activist in the student wing of the Rashtriya Swayamsevak Sangh, a right-wing Hindu organization.
He was so engrossed in R.S.S. work that the first two or three times he was summoned by a distant relative, the head priest of the Gorakhnath Temple, he “could not find the time,” he said.
But religion and politics were fast converging. Gorakhnath Temple, long patronized by Nepal’s royal family, had a tradition of militancy: Digvijay Nath, the head priest until 1969, was arrested for exhorting Hindu militants to kill Mahatma Gandhi days before he was shot. His successor, Mahant Avaidyanath, urged Hindu mobs in 1992 to tear down a 16th-century mosque and build a temple there, setting off some of the bloodiest religious riots in India’s recent history.
When Adityanath announced his intention to join the temple, his father, Anand Singh Bisht, forbade it, he said in an interview. But Adityanath left anyway. Years later, Mr. Bisht burst into tears at the memory.
Mr. Bisht did not learn that his son had become a monk until four months after the fact, he said. Mr. Bisht rushed to see his son at the temple, and found him transformed, his head shaven and his ear pierced in a painful ceremony said to unlock yogic powers.
“I said, ‘Son, what have you done?’ I was shocked,” he said. “That was my child’s desire and so he was there. Then I gave my permission to go ahead. I had no choice.”
Adityanath won a seat in Parliament, the first of five consecutive terms. Among his advantages was a new group he had formed: the Hindu Yuva Vahini, or Hindu Youth Brigade, a vigilante organization. The volunteers, now organized to the village level and said by leaders to number 250,000, show up in force where Muslims are rumored to be bothering Hindus.
Vijay Yadav, 21, a volunteer lounging at Gorakhnath Temple in Gorakhpur on a recent day, said he had recently mobilized 60 or 70 young men to beat a Muslim accused of cow slaughter. They stopped, he said, only because the police intervened.
“All the Hindus got together and the first slap was given by me,” he said proudly. “If they do something wrong, fear is what works best. If you do something wrong, we will stop you. If you talk too much, we will kill you. This is our saying for Muslims.”
During the first five years after the H.Y.V. was formed, 22 religious clashes broke out in the districts surrounding Gorakhpur, a city in Uttar Pradesh, in many cases with Adityanath’s active encouragement, said Manoj Singh, a journalist in Gorakhpur. In 2007, Adityanath was arrested as he led a procession toward neighborhoods seething with religious tension.
Even then, Mr. Singh recalled, the officer who arrested Adityanath stopped first to touch his feet as a gesture of reverence.
For India’s frenetic 24-hour cable television world, Adityanath’s first months as chief minister of Uttar Pradesh were a windfall. Arriving in Lucknow, a city weary of a corrupt bureaucracy, he projected a refreshing toughness and austerity.
His first orders were unabashedly populist. The police were dispatched in “anti-Romeo squads” to detain youths suspected of harassing women. Inspectors shut down dozens of meat-processing plants, a major source of revenue for area Muslims, for license problems.
Vishal Pratap Singh, a Lucknow-based television journalist, noted that Adityanath was a “totally changed man on camera,” careful to avoid comments offensive to Muslims.
Still, Mr. Singh said, his ratings are sky-high, and the reason is obvious.
“Like Modi, he speaks for the Hindus,” he said. “He is a staunch pro-Hindu guy. Within his heart, he is a totally anti-Muslim person. That is the reason he is so likable.”
Political observers in Delhi are watching him as one might watch an audition. Journalists filed reports of his first 100 days last week, and some were lukewarm, noting his failure to contain violent crime.
Neerja Chowdhury, an analyst, said Adityanath has two years to establish himself as an effective administrator.
“Remember, he is 20 years younger than Modi, and he is a known doer, so if he manages to deliver on some fronts, he would then become a possible candidate” in 2024, she said.
“India is moving right, that is a given,” she added. “Whether India moves further right, and Modi begins to be looked upon as a moderate, I think that only time will tell.”
Adityanath may be interested in rebranding himself a mainstream politician, but his followers in the H.Y.V. do not all agree.
During the days after the election, some 5,000 men came forward to join the H.Y.V. every day, prompting organizers to stop accepting applicants, said P. K. Mall, the group’s general secretary.
Sonu Yadav, 24, of Gorakhpur, who has served in the H.Y.V. for five years, said he had been disappointed by Mr. Modi’s tenure.
“We voted for Modi because Yogi endorsed him, but we are disillusioned,” he said. He went on to refer to the 2002 riots in the state Mr. Modi led, which his critics say he allowed to rage for several days, leading to more than 1,000 deaths.
“All of us in our colony felt that Modi would allow us to kill Muslims,” he said. “Muslims were scared. But nothing happened. When Yogi became chief minister, they were scared again.”
For now, as Adityanath establishes a more mainstream reputation, Mr. Yadav and his friends have been told by H.Y.V. leadership to cease all violent activities and instead perform community service. Vijay Yadav, Sonu’s friend, openly chafed at the new orders.
“This thing is going on in Yogi’s head that my shirt should not get a stain,” he said. “I couldn’t care less for his stained shirt. I can’t do good work and avoid getting a stain.”
He noted, by way of example, the recent beating death of a 62-year-old Muslim man whom vigilantes abducted and interrogated about a neighbor’s alleged love affair with a Hindu girl.
Vijay Yadav’s comment on the man’s death was a local proverb: “Along with the wheat,” he said, “small insects will get crushed.”