PM Manmohan Singh has described the nuclear deal as "momentous"
India's Prime Minister Manmohan Singh is due to leave for the United States and France for a 10-day visit.
Officials hope the US Congress will approve the civil nuclear deal with India before Mr Singh meets President George Bush on Thursday.
Earlier this month, the Nuclear Suppliers Group lifted a ban that had stopped India from getting access to the global atomic market.
Once approved by the US Congress, the nuclear pact would be completed.
Manmohan Singh's first diplomatic stop on his tour is New York where he will attend the United Nations General Assembly.
He will make a brief visit to Washington on Thursday to meet President George Bush.
In New York, he is also due to meet Asif Ali Zardari, Pakistan's newly elected president.
Later, Mr Singh is due to visit Marseille to attend an India-EU summit.
India and France negotiated a nuclear co-operation accord during French President Nicolas Sarkozy's visit to Delhi in January.
Indian and French officials say the agreement is ready for signature.
India says the deal with the US is vital for it to meet its civil energy demands.
But critics say it creates a dangerous precedent - effectively allowing India to expand its nuclear power industry without requiring it to sign the Non-Proliferation Treaty (NPT) as other nations must.
India would get access to US civilian nuclear technology
They say the deal would undermine the arguments for isolating Iran over its nuclear programme and be a disaster for international non-proliferation efforts.
The agreement is the centrepiece of US efforts to bolster ties with India.
Earlier in September, the deal crossed a crucial hurdle when the 45-nation NSG approved it.
Mr Singh said the decision marked "the end of India's decades-long isolation from the nuclear mainstream and of the technology denial regime".
The US restricted nuclear co-operation with India after it tested a nuclear weapon in 1974.