As veteran social activist Medha Patkar prepares for her first battle as a politician, she faces an irony of electoral democracy. In many ways, of all her competitors she is the best match for her constituency. But the reason she is suitable also makes it hard for her to communicate this fact to voters.

Patkar, 59, will represent the Aam Aadmi Party in Mumbai North East, which is home to some of the most economically depressed communities of Mumbai's six parliamentary constituencies. It houses the city's biggest garbage dumping ground and its most squalid slums.

As someone who has worked for four decades among the country's most marginalised communities, Patkar is campaigning in her natural habitat. She is familiar not just with the constituency's socio-economic texture; she knows the lay of the land. She grew up in a locality bordering this constituency, and even though her involvement with various struggles took her all over the country, she has returned here several times over the years, in different avatars.

She did an MA and MPhil in social work at the Tata Institute of Social Sciences, which falls within the constituency, and did fieldwork for her graduate studies in a nearby slum. In 1973, she helped set up a non-profit group called Apnalaya, which supports communities that work in the dumping ground, and worked with it for three years. She set up a range of services in another local slum. In 1995, she flagged off the National Alliance for People's Movements, an umbrella body of about 250 organisations spread across 20 Indian states, from her alma mater. She returned this year to launch her campaign for the forthcoming general election.

Aside from the settlements in which she has actually worked, in other slums, Patkar faces the arduous task of announcing herself and her party to voters. For as she campaigned last week in Gautam Nagar, a Muslim-majority slum, not many people seemed to have heard of her, and fewer of the Aam Aadmi Party.

Patkar may have spearheaded the Narmada Bachao Andolan, a three-decade struggle against the displacement of tribals from their land by dams along the Narmada river, one of the great people's movements of post-Independence India, but news of that had not reached Gautam Nagar.

"I find it strange to have to take into consideration the numerical strength of various groups in my constituency, whether linguistic or economic," said Patkar, when asked what she found most difficult about electoral politics. "I never had to do this when I was part of just a social movement. Also, I have to keep talking about myself. That's also not easy."

To reach out, she has undertaken gruelling walking tours, trying to cover as much ground as she can in what is a huge constituency of two million people, encompassing six assembly constituencies. Setting off from the party office in Gautam Nagar, she stopped every ten feet or so to talk to people.

At one stop, she asked a woman hawking vegetables from a cart whether she'd had to pay the police to ply her trade. "Don't give your money to these people," she said, pointing to two or three men in uniform standing nearby and trailing her and the two dozen AAP members that day. "Come and tell us if you are being harassed," she said.

To another group of people, she spoke about how a nexus between builders and politicians kept the poor from living in decent homes. "If you want to change the nature of politics," she said, holding up a broom, the electoral symbol of the Aam Aadmi Party. "All of you must come out and vote. If you think what we are saying makes sense, pick the broom, so we can sweep out corruption."

In this election, Patkar faces Sanjay Dina Patil, the area's current member of Parliament. He represents the Nationalist Congress Party, an ally of the Congress, which heads the ruling coalition in Maharashtra and at the Centre. Also in the fray is Kirit Somaiya of the Bharatiya Janata Party, the main opposition party both in the state and the Centre.

In the previous election, Patil beat Somaiya by less than 3,000 votes, the narrowest  margin in Maharashtra. Patil managed to win only because the Maharashtra Navnirman Sena, which split from the Shiv Sena in 2006, put up a candidate who ate into the BJP's votes. The Shiv Sena is a long-time ally of the BJP, and the three parties have overlapping vote bases.

This year, the MNS, which is focusing its efforts on the state election due in October, has announced only six Lok Sabha candidates and does not seem likely to run in this constituency. This is good for the BJP, but makes the contest harder for Patkar, for she is more likely to wean away traditional Congress voters than BJP supporters.

With all that she is up against, why did Patkar finally decide to cross over to electoral politics?

"It's not that we were frustrated outside the government,"  she replied. "But we need to fight both internally and externally [because] despite our achievements, they stall the implementation or even [set] us back. Corruption is causing leaders to act illegally and irrationally. At the same time, I am concerned that it [getting involved in electoral politics] should not hurt the social movements."

"So far there was no space in electoral politics," she said. "The Aam Aadmi Party has provided that space, and the AAP itself was formed because of social movements."

Some of her support is likely to come from the middle-class colonies that also populate the constituency, where her face and name immediately resonate with many residents. They have read about her in the newspapers and have seen her on TV.

Two hours after setting out from the AAP office at noon, she entered the first middle-class housing colony. An AAP member carrying a tape recorder attached to a speaker pressed a button to start one of many  pre-recorded Hindi slogan with a rhythm and alliterative punch that is lost in translation: Here is your candidate Medha Patkar, of the Aam Aadmi Party. We are not a party but a movement; we face not an election but a challenge; we are here to change the nature of politics.

Some residents came to their windows, many more walked down to the open rectangular area marked off by buildings on three sides. One of them was Anil Ganwat, who told Patkar that the AAP has picked the wrong candidate in a constituency in rural Maharashtra.

"Forget the party," said the 57-year-old trader, when asked about his views about AAP and Patkar. "I have voted for the Congress-Nationalist Congress Party alliance in the past, but today I support Medha Patkar. She is such a good social worker. The NCP hasn't done much. Its candidate hasn't come here even once."

Saraswati Srinivasan, another resident, had also come down after hearing the announcements. Her parents are from Kerala, but she was born and brought up in Mumbai. "We are fed up with the Congress's casteism, goondism and corruption," she says. "It has no leaders. Sharad Pawar was a good leader. Now there is Modi. But Medha Patkar is a very good social worker. She's done work for the poor. She has no personal ambition. She has sacrificed her life for other people. We need people like her."

In this colony and others that Patkar visited that day, she, rather than the AAP, was the star draw. All afternoon, similar discussions took place in other middle-class housing colonies with their heterogeneous, pan-Indian composition that is typical of Mumbai. It was a working day and siesta time for those at home, yet a small group of residents always came out to meet her, offering her water and food, telling her how much they admired her.

Owners of small businesses on the main roads along the way, a very different socio-economic group, spanning political affiliations, also recognised her, and said they respected and admired her. Mahendra Rathod, 35, was among them. He runs the Sai Kripa medical store a few meters away from the AAP office in Govind Nagar, a slum from which Patkar's rally began that day.

Originally from Rajasthan, he supports Narendra Modi and criticises the AAP's Arvind Kejriwal. "Kejriwal did no work," Rathod said of the former Delhi chief minister, who resigned after six weeks in office. "It's very easy to criticise others. Let him show that he can run a government at least for two years. If you ask me, the AAP is a temporary phenomenon. But Medha Patkar is different. She has been a social worker for many years, and has worked for the poor."