Communists have a strong tradition in West Bengal
The current political stand off between Prime Minister Manmohan Singh and his leftist allies over the Indo-US nuclear deal has brought back coalition tensions that have become more or less a permanent feature of Indian politics since the 1990s.
But this time the situation has highlighted the dilemma of the left rather than putting the ruling UPA government in trouble.
The leftist parties have made it clear that the nuclear deal is not acceptable as they perceive it to be detrimental to India's independent foreign policy.
Despite assurances from Mr Singh and Foreign Minister Pranab Mukherjee that the deal will not affect India's right to carry out another nuclear test, the leftist parties are not backing down.
But what next? Are the Communist Party of India (Marxist) and the Communist Party of India, along with their smaller partners, in a position to topple the government?
While the leftist leaders are huddled together in a meeting to hammer out future strategy, the CPM patriarch and former West Bengal chief minister, Jyoti Basu, has ruled out withdrawal of support to the government.
Veteran communist Jyoti Basu played down the government spat
"We have said that we are not satisfied. But we do not want to topple the government as it would pave the way for the communal BJP to come to power," Mr Basu told reporters in Calcutta.
The leftists seem to be faced by two arch enemies - the US and the arch rival Bharatiya Janata Party. The leftists cannot afford to appear in league with either of them.
Keeping this predicament in mind, Mr Singh took a calculated risk and delivered his master stroke last week, daring the leftists to withdraw support from the government.
He knows that however aggressive their stance, they cannot afford to bring down the government.
The leftist leaders kept quiet about their meeting with Mr Singh but the PM decided to make his views public.
In the Calcutta-based Telegraph, Mr Singh said: "I told them that it is not possible to renegotiate the deal. It is an honourable deal, the cabinet has approved it; we cannot go back on it. I told them to do what they want to do, if they want to withdraw support, so be it."
This appears a well thought-out demonstration by the otherwise amiable and soft-spoken prime minister of his assertiveness and ability to deal with his allies.
The leftists and the UPA government have other differences, particularly on Mr Singh's pro-market economy policies.
They have in the past accused the government of deviating from the Common Minimum Programme, a joint policy document that provides the general guidelines for the government.
In June 2005 the leftists boycotted a key meeting saying the government was pursuing policies without taking the left into its confidence.
The leftist parties, who back the government without being a part of it, were also angered by what they saw as US leverage on India over a UN vote on Iran in September 2005.
Although they have only around 60 MPs in a House of 542, many feel their political clout far outweighs their strength.
Mr Singh is showing them he knows how to stick by a decision.
"They are our colleagues and we have to work with them. But they also have to learn to work with us," he said.
For now the leftists are pressing on - calling for a discussion on the issue in parliament.
However, many of their threats to the government are merely aimed at placating the largely anti-US voters in three states - West Bengal, Tripura and Kerala - where the leftist parties are in power.