CALCUTTA, India » The door opened, and out came Didi, as everyone knows her. Didi means Big Sister, but Mamata Banerjee is hardly big, at least in size. She is barely 5 feet, dressed plainly in a simple cotton sari and plastic sandals. Yet, as she stepped out of her tiny house, Didi began barking orders that sent her covey of male aides into a solicitous tizzy. It was time to wage her political insurgency.

"Go! Go! Go!" she shouted as she slid into a small black car and the driver lurched into the tumult of a city of 15 million people. "First, we are going to the hospital!"

It was Sunday, and like almost every other day during the past two decades, Banerjee, 56, continued her unswerving pursuit of toppling one of the most entrenched political machines in the world. The Communist-led Left Front government has won seven consecutive elections and dominated the state of West Bengal for more than 30 years even as the state, once an intellectual and economic capital of India, has suffered a gradual decline.

Now, with new elections expected to be called no later than May, the Left Front appears on the verge of being beaten by a woman who, quite against convention and expectation, is emerging as one of the most powerful and unpredictable politicians in India. If Banerjee wins, she will join a group of regional leaders whose successes are reshaping the Indian political map.

"We have been fighting this battle for a long time, since my student days," she said as the small black car sped through the streets of Calcutta. "We have been the only and lonely people who have opposed them."

There are 90 million people in West Bengal, more than in Germany, and for many of them Banerjee is the blunt instrument knocking down their own Berlin Wall. Her admirers regard her as an elemental force as much as a politician. She is unmarried, and when asked what she does for entertainment, or whether she likes to travel, she seemed incredulous. "Entertainment?" she said, repeating the word. "In my life?"

Her ideology is simple, if rigid: getting rid of the Left Front and the Communist Party of India-Marxist, or CPM, the majority party in the front. Yet, despite the tingly anticipation of change and the palpable excitement among many voters, even some of Didi’s most ardent supporters admit to a slightly nervous question:

Is West Bengal’s blunt instrument also capable of governing the state?

"What are Mamata’s politics?" asked Mahasweta Devi, one of Calcutta’s most famous intellectuals. "It is very difficult to say. We’ve seen that she is against the CPM. Nothing more than that."

And for now, that is what matters.

In West Bengal, politics is often waged like war, and a bloody battle has just occurred. Two days earlier near the village of Netai, at least seven villagers were killed and others were wounded outside an armed camp controlled by the CPM. These camps, scattered across the state, are controversial: The party says the camps are for combating the Maoist rebels steadily encroaching into the countryside, but critics, including Banerjee, say the camps serve the political purposes of the CPM by intimidating villagers during the lead-up to the state elections.

She had already driven overnight to the scene of the shooting and then returned to Calcutta for a rally the previous night with almost 100,000 people. At the rally, as smoke floated over the dais and balloon-tied banners bearing her face floated into the air, she blamed the Left Front for the killings and reminded the crowd, if indirectly, that she, too, had felt the blows of political violence. It is the crucible of her political story.

The daughter of a teacher, Banerjee joined the student wing of the Indian National Congress Party while attending a women’s college in Calcutta. By the late 1970s, the CPM had taken control of West Bengal and Banerjee was a rising star of the opposition, having won a seat in Parliament and later serving in ministerial positions in New Delhi. But as the Congress Party began to reach out to the Left Front as a potential coalition partner, Banerjee bolted to form her own party, the All-India Trinamool Congress. Barely a year later, while leading a march near her home, her skull was fractured by a CPM cadre, leaving her hospitalized for months.

"They have attacked me many times," she said, explaining why her politics are so personal.

As her car moved through traffic, she rolled back her sari to show long scars on both elbows. She touched a spot on her jaw where the skin was repaired by plastic surgery.

"From my belly to my back to my eyes," she said. "I’m covered in these things."

At the hospital, television cameras surrounded her. Victims from the Netai attack had been transferred here for medical care, and she was making an inspection. Inside the hospital, overflow patients draped in dirty red blankets were lying in the hallways as she swept by. Men were almost running to keep pace. When she reached the victims, she did not smile or offer the usual politician gestures of empathy but instead delivered a stern message for the medical staff.

"Are you taking care of them?" she asked in Bengali.

Then she was gone, back through the hallways, back outside for a few words for the cameras and then back into the small black car.

"Go! Go! Go!" she shouted as faces and cameras press against the window, and the car slowly moved forward.

Now she is smiling, giggling even. The small black car has delivered her to the W.B. National University of Juridical Sciences at the edge of the city. More television cameras are waiting as Banerjee sweeps inside to join a panel discussion of election reform. The panel is filled with New Delhi heavyweights: the head of the national election commission, the finance minister, the law minister, a few others. She has slipped on a pair of gold-rimmed glasses and whispers something into the finance minister’s ear, giggling. He seems to grimace.

From New Delhi, the view of Didi is different, as if altered by a different prism. For two decades, she has floated in and out of power in India’s capital, aligning her Trinamool Congress with different coalition national governments while waging her real fight in West Bengal. Her tenacity and almost Gandhian simplicity, if central to her identity in West Bengal, are sometimes framed in a less flattering light in India’s capital, where many in the political class regard her as erratic, immature or unpolished. Didi stories are fodder in the Delhi newspapers; recently came a report that she had consulted a numerologist, who had advised her to add an additional ‘a’ to the end of her name for good luck.

More pertinent are questions about her temperament for governance. In the past, she has resigned from various ministerial positions and staged acerbic protests on the floor of Parliament. Since 2009, the Trinamool has been part of the governing national coalition; as a dispensation, Banerjee was given leadership of the Railway Ministry, allowing her to sprinkle patronage and projects on West Bengal. Yet her critics point out that the railway budget is now in disarray and blame her for focusing more on politics in West Bengal than on the railways.

And yet in West Bengal, that suffices for the moment. At the university, the election panel is a dull, dutiful affair until Banerjee rises for her turn to speak. She is barely taller than the lectern as she talks about democracy, the need for fair elections and how the Left Front has dominated the state for so long.

"For 35 years, there has been no change," she says, as the audience stirs. "This time, I think there will be."

© 2011 The New York Times Company