She spent her life fighting communists but is the biggest obstacle to economic liberalization in India today. She is the leader of a small regional party but wields more power than the prime minister.

Mamata Banerjee, the chief minister of the state of West Bengal, is a rising force in Indian politics, and Secretary of State Hillary Rodham Clinton paid a special visit to Kolkata this month to meet her.

The 57-year-old Banerjee — determined, resolutely populist and hardworking, yet eccentric and intolerant of dissent — holds the balance of power in India’s coalition government and has used that political might to huge effect.

Time after time, Prime Minister Manmohan Singh’s efforts to introduce economic reforms have foundered because of Baner­jee’s opposition. Time magazine recently listed her among the world’s 100 most influential people, and 25 out of 50 CEOs surveyed by a leading Indian newspaper last week said she was the biggest stumbling block to economic growth.

Banerjee is the personification of a fundamental change that is transforming Indian politics: the declining vote share of the country’s two main political parties and the rising influence of regional parties.

To some, she also personifies a fear that politics will fragment to such an extent that India becomes almost ungovernable, that populists pandering to local interests will block important policy decisions.

“We are not Marxist or capitalist, we are for the poor people,” she said in her first major interview with a foreign newspaper. “Our policy is very clear: whatever policy will suit the people, whatever policy will suit the circumstances, whatever policy will suit my state.”

Nicknamed “Didi,” or elder sister, Banerjee wrested power last May from a communist government that had ruled the state of West Bengal for 34 years. But she has been no better for business and investment than her predecessors were, to the dis­appointment of those who had hoped that the vanquishing of the communists from their biggest foothold in the country would help revitalize eastern India. On the national stage, she holds just 19 seats in the 543-seat Parliament but wields immense influence.

In October, Singh’s government announced a long-promised reform: Foreign supermarket chains such as Wal-Mart would be allowed in. Just 12 days later, worried about the future of small shopkeepers in her state, Banerjee forced the government to back down.

To protect the poor, she has blocked attempts to raise gas prices, despite huge subsidies that are bleeding government finances, and overturned a small increase in railway fares. She opposes legislation that would open the country’s banking, insurance and pension sectors to more foreign investment.

Yet in what may have been shrewd diplomacy, or a sign of a genuine personal rapport, Clinton embraced her warmly. A “remarkable” experience, the secretary of state said of their hour-long discussion, which was characterized as “warm, vibrant and energetic.”

Clinton talked of the “common bond” she shares with women who have broken through barriers of discrimination and braved the fire of electoral politics. Indeed, Banerjee claims to be the only woman who has risen to political power in South Asia without being the widow, orphaned daughter or former girlfriend of an established leader.

Anti-communist struggle

A poor schoolteacher’s daughter, Banerjee never married and still lives in a single room, just 8 by 8 feet, in a Kolkata neighborhood beside a foul-smelling open drain. A member of Parliament for India’s Congress party at age 29, she left the party in 1997 over what she deemed an unfair denial of the leadership role in West Bengal. She then formed her own party, the Trinamool (grass-roots) Congress, to take on the communists.

The communists controlled every aspect of life in West Bengal during their long rule, politicizing the police and even the education system by putting party workers in key positions and banning English from state primary schools for 25 years. Militant trade unions became so powerful that they virtually ran factories in this state of 91 million people.

Pointing to the scars on her elbows and the damage to her wrists, she recalled shielding her head from repeated beatings with sticks and iron rods during protests. She was often hospitalized, and she nearly died after a 26-day hunger strike.

She remains popular among the poor, but her populist decisions and growing intolerance of dissent have alienated many middle-class Bengalis who had welcomed her victory a year ago.

While in the opposition, Banerjee fiercely defended farmers’ rights against clumsy attempts by industry and government to seize their land to make way for factories — forcing Tata Motors to abandon plans in 2008 to set up a car factory. But in government, her failure to design a workable alternative land-acquisition policy has become a barrier to the investment that the impoverished and crowded state desperately needs, business leaders say.

Under communist rule, the technology services company Infosys was poised to set up a software-development center that would have brought more than 10,000 jobs. Banerjee refused to allow it the status of a special economic zone, and Infosys last month put the project on hold “indefinitely.”

Banerjee says the communists have left her state bankrupt, saddled with a $40 billion debt. The rusting hulks of abandoned factories still ring Kolkata, testament to decades of economic mismanagement under communist rule.

But critics say Banerjee has no strategy to repair the damage. She says she cannot afford to give tax breaks to industry, but she has found the money to hire 90,000 extra teachers and police personnel, give monthly stipends to Muslim imams, and symbolically remove all vestiges of communist rule by painting every railing and bridge in Kolkata blue.

Her cabinet wins widespread respect, but she keeps all her ministers cowed, critics say, and is the only person empowered to make any real decisions.

“She has tremendous rustic intelligence, but she has yet to get to grips with the realities of the economic situation she is facing,” said prominent businessman Sudhir Jalan.

Yet Jalan said Banerjee is beginning to soften toward industry, to realize that she has a problem, even if she doesn’t yet know how to solve it.

To attract American investors, she put her best foot forward.

“We cannot offer what other states can offer, because of our situation — but we can extend our cooperation from the heart,” she said. “We can touch your heart, but maybe not financially.”

Still, she is determined to keep her election pledges, and that means no foreign supermarkets. “I am ready to die, but I cannot cheat the people,” she said.

Conspiracy theories

But it is her distrust of criticism, her sense that anyone who dares to oppose her is part of some vast communist conspiracy, that has done the most to alienate the intelligentsia in one of India’s foremost cultural centers.

When a woman was gang-raped, Banerjee accused her of fabricating the case to “malign” her government. When a chemistry professor shared a cartoon by e-mail mocking the chief minister, he was beaten by her party workers and arrested.

Asked about the cartoon, Banerjee launched into a tirade about how her Marxist political opponents were plotting with Maoist rebels to discredit and kill her, in league with Pakistani intelligence and financed by North Korea, Venezuela and Hun­gary.

“They have given me the death sentence, and every day they are spreading this superimposed photo, on Facebook, on Internet or in the e-mail, through some false, camouflaged name,” she said.

Optimists say the rise of regional parties is not necessarily bad for India, especially if states win more power to shape their own economic policies, allowing development to proceed at a different pace in different parts of the country.

Some are also inclined to give Banerjee the benefit of the doubt, to argue that she is learning on the job.

“She is intolerant,” said Ananya Chatterjee, a journalism professor and Banerjee supporter. “But you needed someone who is a little bit intolerant, who is a little bit crazy, to throw the left out of power after so long.”