At stake are 39 parliamentary seats in Tamil Nadu, a state known for its ancient Hindu temples, its modern auto industry - and a history of electoral landslides. (Agencies)
With pollsters predicting that no party will win a majority in the 543-seat parliament, the caucus returned by India's sixth-largest state could hold the key to forming a government after the five-week general election that starts on April 7.
Tamil Nadu Chief Minister Jayalalithaa Jayaram - or 'Jaya' to her fans - is riding a wave of popularity that could take her AIADMK party's seat count to 27, according to one survey, potentially casting her in a new role as national powerbroker.
Her party is one of many regional groups whose proliferation over the past two decades has made it impossible for national parties to rule alone in India. Two more are led by female firebrands, Mamata Banerjee in West Bengal and Mayawati in Uttar Pradesh.
The portly, fair-skinned Jayalalithaa bears little resemblance to the singing, dancing heroine of 1960s Tamil cinema. But, at 68, she is probably more popular than she has ever been.
Hopping around the state by helicopter, she is addressing enthusiastic crowds, including one last week near Tiruvannamalai, a holy site where Hindu pilgrims, in an act of devotion, walk around a mountain barefoot at full moon.
"She is the only one who gives voice to the Tamils," said tea seller M.K. Baskran, an AIADMK grassroots organiser, to noisy agreement from fellow supporters. Others thanked Jayalalithaa for food handouts that sustained their families.
Pundits in Chennai, the former port of Madras founded by the British in the 17th century, describe Tamil Nadu as a 'sweep' state; not a swing state. That is the result of another British legacy: first-past-the-post voting.
"A gap of 4-5 percentage points in the popular vote between the first and second party gives you a hugely disproportionate result," N. Ram, publisher of The Hindu newspaper, said.
SPLIT LIKE AN AMOEBA
Cinemas in Chennai are screening a digitally restored version of Jayalalithaa's 1965 movie 'One Man In A Thousand', in which she plays a damsel in distress saved by leading man M.G. Ramachandran - or 'MGR' - in the role of a swashbuckling pirate.
As well as bringing her extra publicity, the film revival holds the key to regional politics: It was actor-turned-politician Ramachandran who formed the AIADMK party four decades ago when he was kicked out of the DMK.
"The DMK split was like an amoeba dividing or an earthworm being cut in two," said Chennai journalist and commentator Gnani Sankaran. "These two formations are the major players - always. The others are minor players - always."
The DMK is still led by the 89-year-old M. Karunanidhi, who fired Ramachandran in 1972. But it is his son M.K. Stalin - named in honour of the late Soviet dictator - who is leading the party's rearguard action.
"There's a wave against the Jayalalithaa government's misrule, massive corruption and undemocratic governance," Stalin told the Economic Times last week. Neither party commented for this story.
The DMK is, however, driven by in-fighting after quitting the Congress-led government in New Delhi a year ago. The party on Tuesday expelled Karunanidhi's second son, a former cabinet minister, having banned him from the party slate for disloyalty.
The DMK, the Congress and a minor ally won 27 seats in Tamil Nadu in the 2009 election. A decade ago, their alliance won all 39 seats, aiding the return to power of the Nehru-Gandhi dynasty that has dominated Indian politics since independence.
Congress, isolated, now faces a wipeout in the state. In one sign of looming defeat, Finance Minister P. Chidambaram has bowed out of contesting his family bailiwick in Tamil Nadu, giving his son the chance to cut his political teeth.
And, although the Bharatiya Janata Party (BJP) is poised to emerge as the largest parliamentary party - with 195 seats according to this month's poll by the NDTV news channel - the Hindu nationalist opposition party has no base in Tamil Nadu.
Even with its allies, the BJP could fall some 40 seats short of the 272 needed for a majority in the national parliament, according to the poll. That is where regional players like Jayalalithaa come into the equation.
Her reluctance to criticise the BJP's candidate for prime minister, Narendra Modi, and a past dalliance with his party, suggest she is positioning herself for power and influence in the next government.
"Jayalalithaa is both in the BJP alliance and not in it," said N. Sathiya Moorthy, director of the Chennai chapter of the Observer Research Foundation, a think tank.
Her ability to dictate terms - or even stake a claim to the premiership - would depend on how big a "last mile" problem the BJP faces in cobbling together a majority.
A weaker BJP result would strengthen Jayalalithaa's hand, as she eyes the alternative of a coalition made up of regional parties, often referred to as a 'Third Front'.
"Within these different groups, anyone with 25-30 MPs is going to be contender for the prime minister's position," said commentator Sankaran. "And if Jayalalithaa has 30 MPs from Tamil Nadu, she will be able to demand the prime ministership."
At stake are 39 parliamentary seats in Tamil Nadu, a state known for its ancient Hindu temples, its modern auto industry - and a history of electoral landslides.