NEW DELHI: India’s coalition government underwent a major shake-up on Friday with the dominant Congress party pushing on with a controversial nuclear deal with the US and ditching left-wing allies.

After discussing what politicians described as the “modalities” of a divorce from the Congress-led government because of the pact, a four-party bloc of Communist and leftist parties gave the government days to clarify its position.

The Congress party, however, was working to avoid being forced into early elections and getting the atomic deal through - negotiating a new alliance with the socialist and regional Samajwadi Party (SP). SP leader Mulayam Singh Yadav met Premier Manmohan Singh and Congress party chief Sonia Gandhi separately to finalise their agreement, officials said.

After talks with Singh, Yadav told reporters that “national interest is more important than politics” - seen as a sign that a deal to reshape India’s ruling alliance was close.

Senior Congress leader Veerappa Moily told NDTV news channel: “We have the numbers now. Their (Samajwadi Party’s) help has been very timely.”

The nuclear deal - agreed in principle in 2005 - would allow India to buy atomic power plants and technology despite not having signed international non-proliferation pacts.

Prime Minister Singh argues the pact is crucial for India’s energy security.

He is lined up to meet US President George W Bush on the sidelines of the G-8 meeting in Japan next week, taken as another sign that Congress was blazing ahead with implementing the pact.

Tensions between Singh and the communists have been running high for months, with the left-wing threatening to pull the plug on the coalition and force elections earlier than May 2009 as scheduled. India’s left says the deal undermines the country’s traditional status as a beacon of the non-aligned movement, and that allowing UN inspections of the civil nuclear programme - as demanded by the Americans - would harm the strategic weapons programme.

After their meeting on Friday, top Marxist leader Prakash Karat set Monday as a deadline for the government to clearly declare whether it was proceeding with the deal.

“We wish to know... whether the government is proceeding to seek the approval for the safeguards agreement by the IAEA,” Karat told reporters.

“Please let us know by July 7, 2008,” he said adding that the left-wing parties would meet a day later for a final decision on withdrawing support.

Karat’s colleague Sitaram Yechury however signalled that the withdrawal of support would not happen before Thursday when Singh returns from Japan.

“We will keep the dignity of the country and the prime minister ... when we take the decision,” he said. Congress, meanwhile, brushed off the ultimatum and said it “cannot be subjected to deadlines.”

“We are happy that other parties (working) in the national interest are slowly converging to our view point,” spokesman Abhishek Singhvi told reporters. “We are working towards triple objectives - to do a nuclear deal in national interest, to carry along our allies with us for that purpose and to go to elections as per schedule” in May 2009.

The United States has been pressing India to move on the deal before the end of President Bush’s tenure, warning the pact may not survive in its current form under the next administration.

Before the deal is voted on by the US Congress, New Delhi also needs to earn a waiver from the 45-nation Nuclear Suppliers Group.