Indian PM Manmohan Singh has left for Japan for the G8 summit where he is expected to discuss the civilian nuclear deal with the President Bush.
Mr Singh's leftist allies have set him a deadline of Monday to say if he will proceed with the controversial deal, reported BBC.
But Mr Singh appears to have secured a deal with the regional Samajwadi Party to replace the Communists.
The leftists have opposed the deal saying it would give the US undue influence over India's foreign policy.
India is under pressure from Washington to sign the deal before the US presidential elections in November.
Mr Singh has argued the pact is crucial for India's energy security and reports suggest that his Congress Party-led coalition would go ahead with the deal.
"I will convey to the international community India's belief that climate change, energy security and food security are interlinked and require an integrated approach," Mr Singh said in a statement on the eve of his departure for Tokyo.
India's foreign secretary Shiv Shankar Menon has said that Mr Singh would meet President Bush in Tokyo on the sidelines of the summit on Wednesday.
Reports say Mr Singh is expected to tell Mr Bush that India would be going ahead with the nuclear deal despite the opposition from its allies.
The deal now needs to be approved by the UN's nuclear watchdog, the International Atomic Energy Agency (IAEA), as well as by the 45-nation Nuclear Suppliers Group, which regulates global civilian nuclear trade.
Then it has to be presented to the US Congress for final approval.
The government's Communist allies met last Friday to discuss the when they would withdraw support to the government.
They set a deadline of 7 July for the government to clarify its stand.
The Congress has said it would not be bound by the demand.
Analysts say the decision to withdraw support could come any time now.
But the Congress Party seems on steady ground as it appears to have worked out a deal with the regional Samajwadi Party to secure its support for the deal.
If the Communists withdraw support, the ruling coalition would be reduced to 226 members in the 543-member parliament, a good 46 seats behind the majority mark of 272.
The Samajwadi Party, which has been a traditional political foe of the Congress, has hinted that its 39 MPs could end up supporting the ruling coalition on the nuclear deal issue.
If that happens, the ruling coalition will mop up the support of 265 MPs - only seven short of a majority.
Analysts say that securing the support of another seven members will not be a problem as there are a number of "fence-sitters" from other smaller parties.
Under the terms of the controversial deal, India would get access to US civilian nuclear technology and fuel.
In return, Delhi would open its civilian nuclear facilities to inspection - but its nuclear weapons sites would remain off-limits.
US President George W Bush finalised the nuclear agreement with Prime Minister Manmohan Singh in July 2005.
It overturned three decades of US policy by allowing the sale of nuclear technology and fuel to India.
With President Bush's second and final term in office drawing to a close and presidential elections set for November, the Bush administration is growing increasingly keen to wrap up the deal.
Many analysts and some within the Bush administration believe a failure to conclude the agreement could create a setback for the current momentum in US-India relations.