Arvind Kejriwal sat yards from a police roadblock in the heart of Delhi, surrounded by a cluster of supporters and clutching a microphone. Every now and then he would rail against government corruption, and his supporters would cheer. A couple of hours later, he was hauled off by police and arrested. It was not the first time.
"I'm not surprised [by the government's dismissal of his latest claim]," he said. "I would have been surprised if they have acted on it."
The 44-year-old former senior tax inspector is the face of a mounting anti-corruption campaign that has electrified India. But 10 days ago he stepped over a previously uncrossed line when he levelled allegations of corruption at Robert Vadra, the son-in-law of Sonia Gandhi, the head of India's ruling Congress party. For the first since the Bofors scandal of the late 1980s, corruption claims were being directed at India's most powerful political family.
"Robert Vadra acquired properties worth hundreds [of millions of rupees] for nothing," Mr Kejriwal said at a press conference and produced documents he claimed suggested wrong-doing in transactions with India's largest property developer, DLF. "This massive property buying spree by the son-in-law of the ruling dynasty in the country gives rise to several important questions."
Mr Vadra, a businessman and keep-fit fanatic who is married to Mrs Gandhi's daughter, Priyanka, has adamantly denied the allegations.
In a statement Mr Vadra said: "I am a private, law-abiding citizen who has been engaged in business over the last 21 years. The allegations levelled against me... are utterly false, entirely baseless and defamatory."
DLF has also denied any impropriety in its dealings with Mr Vadra, saying in a statement: "Our business relationship has been conducted to the highest standards of ethics and transparency, as have been our business practices all around."
Of course, Mr Vadra is not like any other "private" Indian citizen. Since the brass handicrafts dealer from Uttar Pradesh married Ms Gandhi in 1997 – an unlikely pairing, many commentators have snootily noted – he has enjoyed a position at the heart of a family that is fawned over like royalty.
A team of government-appointed bodyguards jog behind him during his regular morning runs around Lodhi Gardens in Delhi, and he is excused the requirement of passing through airport security, a privilege that is similarly granted to India's President and the Dalai Lama.
The Congress party initially came out with all guns blazing, accusing Mr Kejriwal of "below the belt" tactics and saying he was trying to attack the party through Mr Vadra. However, the main opposition party, the Bharatiya Janata Party, has been notably slow to seize on the issue.
To Mr Kejriwal's supporters that is not surprising. "There is only one party in this country and that is the parliamentarians," said Haranjit Roy, who had joined the demonstration. "There is only one opposition, and that is the public."
Corruption is a huge, insidious problem in India that has eaten into every aspect of life. The campaign to stamp it out gathered pace after preparations for the 2010 Commonwealth Games embarrassed the nation, and has been fuelled by a series of government scandals, most prominently the mis-auctioning of spectrum licences that cost the country up to $40bn (£25bn) and led to a minister being jailed.
"In India, all people are frustrated by the corruption," said another supporter, Vinod Kumar, who works in a hotel. "Everywhere and in everything there is corruption. The politicians are not with the people, they are with the corporations and the companies... At the next election, Arvind will be our leader."
Mr Kejriwal worked for a number of years as a senior official in the tax collection department, but he quit in the mid-1990s to form a social action group known as the Public Cause Research Foundation. He then became an important player in the campaign to pass a right to information law, a 2005 bill that provided members of the public with access to off-limits government records.
He came to a wider prominence during last year's demonstrations in support of a government ombudsman with far-ranging powers.
After that campaign faltered, Mr Kejriwal decided he needed to be directly involved in politics if he was to challenge the establishment, declaring: "From today, people are entering politics. Corrupt leaders, count your days. All the parties have cheated us. We will not now request, we will not plead. Now it is a full-throttle political battle."
His guerrilla-style tactics have unsettled the political class, which has sought to dismiss his allegations by saying he is simply flinging mud. His supporters retort that a small NGO does not have the resources to mount a full investigation and that the federal authorities should do so.
What is clear is that Mr Kejriwal and his allegations are not going away. Eventually released along with his supporters on Saturday, the activist promised to continue his protest. He has also raised the prospect of making more "explosive" allegations this week.
"This is a political battle," he said, "it's people's politics against corruption."