MEWAT, India — In villages nestled among freshly razed wheat fields, a group of activists, spurred on by rumors, is hunting killers. They hear that these hunters are rounding up their prey by the thousands, snatching them at midnight from ponds and roadsides. They prod them onto stolen cars with heated iron rods, the whispers say, and butcher them.

The victims of these attacks are cows, deeply revered by many Hindus, and the perpetrators of these alleged assaults are mostly Muslims, making the fight a flash point between India’s largest religious groups on the eve of state elections.

Activism over the protection of cows is a centuries-old tradition in India, expressed in the law with most states banning cow slaughter. Muslim Mughal emperors put in place laws to protect cows in the 16th century to promote religious harmony.

In the colonial period, Indian freedom fighters took up cow protection, partly to rebel against their imperial beef-eating rulers.

But during elections, which will come to this state, Haryana, and to Maharashtra on Wednesday, the fight to protect cows and the rumors about their mistreatment have ramped up. There are no reliable estimates of cow killings, so it is difficult to say whether they have increased, never mind to determine the religion of the perpetrators. But that has not stopped right-wing political parties, which have whipped up their base by demanding stricter enforcement of laws against killing cows, and some say that local activists working in tandem with those parties are exploiting religious divides for electoral gain.

Some analysts in India worry that the emergence of Narendra Modi, a hero of the Hindu right, as prime minister has emboldened religious conservatives to embark on sometimes violent campaigns against Muslims, though Mr. Modi himself has steered clear of religious issues.

One such conservative in the northern Indian state of Haryana is Mahinder Pal Singh, who runs a cow shelter. He said he mobilized his network of young men if he so much as heard of a Muslim driving a car late at night that he suspected contained smuggled cows. The work can be deadly: One of his associates was killed six months ago on a midnight raid, he said.

“We’ll catch hold of them, even if our workers are killed,” said Mr. Singh, standing at the shelter’s troughs, where dozens of cows fed and the air was thick with the smell of droppings.

In a nationally televised speech this month, Mohan Bhagwat, the leader of the Hindu nationalist organization Rashtriya Swayamsevak Sangh, urged on grass-roots activists. In the state of Maharashtra, a mob objecting to a temporary slaughterhouse set up for the Muslim holiday of Eid al-Adha earlier this month besieged a train and pelted the police with stones.

In the mostly Hindu state of Haryana, the Muslim-dominated district of Mewat is one place where the smuggling rumors are swirling.

In nearby Jhajjar, local leaders called for a ban on Mewat traders after five cows were found beheaded, gutted and skinned last month, according to a cow protection advocate there. Last week, a Delhi judge imposed life sentences on seven Mewat traders for firing on the police and five years’ imprisonment for cow smuggling, adding that they “belong to the notorious, ferocious and desperate gang of cattle lifters from Mewat known to hit back at police, having no fear of law.”

Religious issues have long been used by political parties to spur voters to the polls. Ahead of elections in Uttar Pradesh this summer, Bharatiya Janata Party leaders spoke out against the often cited but never proven practice of “love jihad,” in which Muslim men reportedly seduce Hindu women, a narrative widely seen as an attempt to polarize voters.

One of the most widely publicized allegations of love jihad was undermined this week when a woman came forward to say that she had willingly eloped with her Muslim boyfriend and that her parents had pressured her into reporting a case of gang rape and forced conversion.

So far, agitation over rumors of cow killings has not reached that pitch. At the B.J.P.’s Mewat office in Nuh, the district’s headquarters, a local candidate, Sanjay Singh, was uncomfortable about overtly linking them to campaign promises.

“This is an emotional issue; this is not an election issue,” said Mr. Singh, sitting before a campaign poster featuring an enlarged image of Prime Minister Modi’s face. “It is a religious issue — it is for the entire Hindu society.”

But earlier in October, a state B.J.P. leader announced that, if elected, the party would work hard to elevate the punishment of cow slaughter to that of murder, according to the Press Trust of India.

Mr. Modi, a longtime member of Rashtriya Swayamsevak Sangh, has kept his distance from contentious religious issues since becoming prime minister, said Neerja Chowdhury, a political commentator.

“But the work is done by others on a local level, and he has not kept them quiet,” she said.

Many Muslims in Mewat complained that the cases that went to court seemed suspect, adding that Hindus dominated the police force in Mewat.

Hafiz Mohammad Hanif, 47, a farmer, said that the B.J.P. was just provoking cow slaughter rumors for the elections.

“Each time there is a cow slaughter, it is a Hindu who does it,” he said. “They kill cows and dump the body parts on our land to vilify us.”

He said that the cow shelters were actually businesses of their own, and that the so-called protection advocates were rounding up stray cows and selling them for profit.

“They’d sell them to me for a high enough price,” he said.

Sher Mohammad, a farmer in a nearby village, said that his son had been accosted by Hindu men a month and a half ago when he was trying to transport a cow the family had bought for milk. Mr. Mohammad’s son tried to persuade them that it was a legitimate sale, but the men pushed the driver out of his seat and drove them to a local precinct, where his son was jailed.

“In this village everyone keeps their own cows and buffalos, but nobody stops the Hindus,” Mr. Mohammad said.

Mahinder Pal Singh, who runs the cow shelter, complained that the Hindu population in the area had fallen precipitously over the years, which he said was part of a Muslim plot. He said that cow smuggling and conversions were designed to weaken Hindus in the region.

“They want to establish a buffer state here where terrorists come for refuge,” Mr. Singh said.

Mr. Singh was most animated when he spoke of his reverence for the cow, whose milk he said could cure AIDS and cancer.

He said that former Prime Minister Indira Gandhi had given 15 Indian cows to the Soviet Union during her tenure, and that the bacteria from the cow milk had helped to protect some residents against the nuclear disaster in Chernobyl.

“We consider cows more worthy than our mothers,” he said.

Though many Muslims in Mewat said that the law of the land should be respected, there was a degree of bafflement at the cow’s place in Hinduism.

More than one resident of Mewat asked about the logic of a law prohibiting slaughter of cows, including Sher Mohammad, whose son had been arrested. “If God has made them to be killed and eaten, what’s wrong in that?” he asked.