NEW DELHI (Reuters) - Sonia Gandhi, the usually reserved and poised leader of the ruling Congress party, leapt from her front-bench seat in parliament last week to grab back a document that a Member of Parliament (MP) had snatched from a government minister's hands.
She caught the MP by the arm, some media reports said, but failed to retrieve the document before it was torn up. A minor scuffle ensued between members of Congress and the offending lawmaker's Samajwadi Party (SP).
The extraordinary drama lasted less than a minute.
But it illustrated the vulnerability of a government that, now reduced to a minority in parliament, depends for its survival on unreliable allies like the SP. Not only will they hamper further economic reform, they could bring the government down and trigger a general election before it is due in 2014.
"It is in their hands to force an election," said M.J. Akbar, editor-in-chief of the Sunday Guardian.
The SP, a powerful regional party from the most populous state, Uttar Pradesh, often votes with the Congress party but it was enraged by the government's support for a bill promoting affirmative action for low castes. The measure had been sought by the Bahujan Samaj Party (BSP), another government ally but a bitter rival of the SP in Uttar Pradesh.
After the SP disrupted parliament for days over the measure, which it fears would disadvantage its many Muslim supporters, the SP lawmaker resorted to desperate tactics, grabbing the bill from the minister as he tried to bring it to a vote. It worked. Parliament adjourned until February without passing it.
The government is effectively tethered to two parties that are sworn enemies and whose efforts to outmanoeuvre each other and win votes in the run-up to 2014 have the potential to bring down Singh's coalition, although analysts agree that right now neither party wants early elections.
"The Congress wants to stay in power and the other two want proximity to power so it is opportunist politics for all three," said Basudeb Acharia, a senior leader from the left-wing Communist Party of India (Marxist).
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The battle between the two parties over the bill left Prime Minister Manmohan Singh with no time to drive through further reforms, including measures to open up the insurance and pension industries to more foreign investment, before the session ended.
It showed for the first time just how reliant Singh is on the SP and BSP to govern a country of 1.2 billion people after a major ally walked out of his coalition in September, wiping out its parliamentary majority.
"India is very dependent on them," political scientist Sudha Pai said. "The government has a good chance to push reforms but a lot will depend on how they manage the two parties."
Presiding over a slowing economy, high inflation and a government accused of corruption, Singh is under pressure to show results before the general election, so he cannot afford a repeat of the largely unproductive winter parliamentary session.
The SP's and BSP's control over nearly one-tenth of the 787 seats in the two houses of parliament combined, and the ease with which they change positions on policy, give them the clout to create political instability and economic uncertainty.
The SP is led by Mulayam Singh Yadav, 72, a former wrestler who harbours prime ministerial ambitions. He opposes many of the government's economic reforms but supports Singh's coalition to block the rise of the Hindu nationalist Bharatiya Janata Party (BJP), the main opposition in parliament.
The BSP is led by Mayawati, 56, a former chief minister of Uttar Pradesh who goes by only one name and is as famous for building sandstone statues of herself and for her love of designer shoes as she is for championing the cause of Dalits, who are on the lowest rung of the caste hierarchy. She has also opposed many of the economic reforms.
Prime Minister Singh has reason to be wary of both leaders.
Yadav has proven repeatedly to be an unpredictable partner, while Mayawati helped topple a BJP-led federal government in 1999 after first promising support in a confidence vote and then siding against it at the last minute.
The government's worry is partly based on the historic antipathy both leaders share for the Congress party, which has ruled for most of India's 65 years of independence from Britain.
Yadav was a political prisoner during the Emergency declared by former Congress Prime Minister Indira Gandhi in the mid-70s. Mayawati grew up scorning what she viewed as the Congress party's patronising attitude towards Dalits.
Yadav and Mayawati have scripted their political success in Uttar Pradesh by marginalising the Congress party and dividing the state's "vote bank" between themselves. Their parties have taken turns over the past 20 years to rule a state that, with 200 million people, has a bigger population than Brazil.
The Congress government, however, is no passive hostage in this political drama. It exploits the rivalry between the BSP and SP, often playing one against the other on policies where their interests are diametrically opposed.
Congress has also long been accused of using the Central Bureau of Investigation (CBI), India's equivalent of the FBI, as a political weapon to harass its opponents. Both Yadav and Mayawati have CBI corruption cases hanging over them, raising suspicions that these are being used to bring them to heel.
Last month, before the winter session of parliament, Singh hosted both leaders at separate meals in an effort to get them to back his economic reform agenda. In the weeks and months ahead, Singh will likely have to engage in more "dinner diplomacy" to try to keep them on side until 2014.
"The SP and BSP are sitting on a wall. The whole strategy is to keep them on the wall," said a government official familiar with the efforts to manage the complex three-way relationship.
"Don't push them enough so they have to come off the wall."
(Writing by Satarupa Bhattacharjya and Ross Colvin, Editing by John Chalmers and Raju Gopalakrishnan)