Decked out in a plain white shirt, white cap and spectacles in the style of Mahatma Gandhi, the septuagenarian Anna Hazare became the unlikely thorn in the side of the Congress party-led coalition when he went on an indefinite hunger strike in April.
Police on Monday denied permission for Hazare to fast near a cricket stadium, putting the activist on a collision course with authorities. Police said he had failed to meet certain conditions, including ending his fast in three days.
Tapping into a groundswell of discontent over corruption scandals in Prime Minister Manmohan Singh's government, Hazare lobbied for a parliamentary bill creating a special ombudsman to bring crooked politicians, bureaucrats and judges to book.
Hazare called off his fast after the government promised to introduce the bill into parliament. The legislation was presented in early August, but activists slammed the draft version as toothless, prompting Hazare to renew his campaign.
A string of corruption scandals has shaken India in recent months, smothering Singh's reform agenda, denting investor confidence and distracting parliament at a time when the economy is hit by inflation and higher interest rates.
Hazare's campaign, fanned by social networking sites and a raucous TV and print media, will be another headache for the Congress Party when government resumes work on Tuesday, the day after India celebrates the 64th year of independence from British rule.
"As soon as the government listens to the majority's demand, we will stop our fast," Suresh Pathare, Hazare's personal assistant, told Reuters by phone.
But this time around, Hazare's fast may not have the same impact as his previous efforts. He has sparked a backlash of his own, with critics saying his methods are tantamount to blackmailing an elected government into changing policy.
"Manmohan Singh remains as weak as he has been," said D.H. Pai Panandiker, head of New Delhi-based think tank RPG Foundation, but "the response to Anna Hazare may not be as strong as he anticipates."
In a sign of how Hazare has made the government nervous, ruling party officials over the weekend launched aggressive attacks on the social activist, saying he too was involved in graft cases.
Congress spokesman Manish Tewari told local media that Hazare was surrounded by "armchair fascists, overground Maoists, closet anarchists... lurking behind forces of right reaction and funded by invisible donors whose links may go back a long way abroad".
Those attacks may backfire among a public increasingly critical of the government. Accused of being a "lame duck", Singh has struggled to regain the policy initiative after scandals, including allegations of bribery and conspiracy in a $39 billion telecoms scam that has sent two coalition politicians to trial.
Reforms such as making it easier to acquire land for industrial projects -- the kind of investment India needs to sustain its 8 percent growth momentum -- are slow to move.
Singh's image took another beating after police, using batons and tear gas, broke up another fast led by a yoga guru in June, prompting the Supreme Court to question the intervention.
Singh used his Independence Day Speech on Monday to focus on corruption, admitting social programmes were plagued with graft, but saying there was no magic wand to end it and that the controversies should not put into question India's progress.
"Those who do not agree with this bill can put forward their views to parliament, political parties and even the press. However, I also believe they should not resort to hunger strikes and fasts-unto-death," Singh said.
Despite its woes, Congress remains in no danger of losing office, mainly due to the inability of the main opposition Bharatiya Janata Party (BJP) to capitalise on Singh's troubles, hit by internal squabbling and its own corruption scandals.
"The real story of the past year ... is not that the Congress and its allies have faltered but that the principal opposition party hasn't been able to take advantage," Swapan Dasgupta, a BJP-linked political analyst, wrote on Friday.