With the government virtually putting the nuclear deal in the cold storage, a disappointed US has started reaching out to parties opposing the agreement in an attempt to garner support.
US Ambassador David C Mulford met Leader of the Opposition L K Advani in New Delhi and is understood to have sought BJP's support for the deal, which is mired in a political controversy.
Mulford is believed to have attempted to assuage BJP's concerns over the agreement. Advani gave him a patient hearing but made no commitments on support to the deal, sources said.
BJP, while favouring a closer strategic relationship with the US, is opposed to the deal as it feels it will affect India's indigenous military nuclear programme and independent foreign policy.
Wednesday's meeting assumes significance as it comes ahead of the planned special session of Parliament to discuss nuclear deal.
The US envoy had earlier met External Affairs Minister Pranab Mukherjee and Foreign Secretary Shiv Shankar Menon to ascertain what the government would do in the face of stiff resistance from Left allies and main opposition BJP.
The US is upset after Prime Minister Manmohan Singh indicated earlier this month that he would not put his coalition government at risk because of the nuclear deal and was ready to live with 'disappointments' if the agreement failed.
The meeting came on a day US Under Secretary Nicholas Burns said time was running out and India needed to act fast.