The Communist Party of India-Marxist (CPI-M) has not ruled out joining or even leading it if the Lok Sabha elections lead to a government that excludes the Congress and the Bharatiya Janata Party (BJP).
But politburo member Brinda Karat says the Left would never support a Congress-led government.
"There is no way we will support a Congress-led government because the Congress DNA is such that it just cannot work with a joint programme," Karat said in an interview amid frantic attempts by Congress allies and even the Congress to make up with the Left.
"It betrayed its own programme in the last five years. It failed utterly as the leader of the coalition - though we were not part of the coalition - because of its mindset, which is a single-party majority mindset," she said of the Congress, which heads India's ruling multi-party alliance.
The CPI-M leader said the Congress had demonstrated that it was "incapable of sticking to the Common Minimum Programme (CMP)", which the Congress, its allies in the government and the Left signed after the 2004 elections.
"At every turn during the last five years, the party had tried to bring in neo-liberal economic programmes."
Even as the Congress stand has softened vis-a-vis the Left, with both Prime Minister Manmohan Singh and External Affairs Minister Pranab Mukherjee making placatory gestures, the CPI-M has hardened its position towards the Congress.
Karat brushed aside the compulsion of cooperating with the Congress in order to keep the "communal" BJP at bay by countering: "Where is the BJP?"
"As far as we are concerned, the Congress has strengthened communal forces through its compromising policies towards Hindutva."
West Bengal Chief Minister Buddhadeb Bhattacharjee has indicated that unlike 1996 - when the party forbade veteran leader Jyoti Basu from becoming the prime minister of a centre-Left government - it might be "possible" for the CPI-M to enter the government this time.
Asked for her view about the CPI-M's likely participation in a new government, Brinda Karat said: "It is neither ruled in nor ruled out." The question, she said, was premature.
"The practice of our party is that once concrete circumstances arise, whatever they be, we discuss it in the Central Committee and take a decision. We did this in the past and we will do this in the future."
Would the Left be willing to lead such a government? "I cannot discuss this," she replied but did not reject the idea outright.
"There are too many ifs and buts here. It depends on the circumstances. Wait and see. At the moment we are asking for a mandate to form a secular alternative government. Let's see what happens."
The party resolution under which Jyoti Basu was prevented from taking up the prime minister's post in 1996 was amended in 2000.
Speaking about it, Karat said: "I would not use the word 'dilute'. On the basis of the experience of 1996, the (amended) party resolution is exactly what I told you. That it is not a matter of principle but of a set of circumstances, and concrete circumstances, on the basis of which the party will take a decision after elections.
"The Left has made it clear that it would help form a secular, non-Congress, non-BJP government at the centre. It would preclude the Congress from the leadership of such a government."
Karat was sharp in her response to Prime Minister Manmohan Singh's overtures to the Left and reminded him that it was not so long ago that he had accused the Left of wanting to make him a "bonded labour".
"Our politics is not determined by the mood of the prime minister. It is detemined by what we believe to be in the national interest. Today national interest requires an alternative secular government.
"The prime minister is saying let bygones be bygones to let secular forces come together and form a government. I feel, at least, partially his wish is going to be fulfilled. There will certainly be a secular government. The other part of his wish, that the Congress leads that government, is not going to be fulfilled."
Brinda was asked if the Left's objection was more to Manmohan Singh than to the Congress. She answered that the CPI-M opposition is not to a leader but the party leadership.
She denied projecting Uttar Pradesh Chief Minister Mayawati as a likely prime minister. "We never projected Mayawati. As far as my party is concerned, there is no question of projecting this or that individual as prime minister. These are matters to be decided after the elections."