"It would be tragic for India to forgo this opportunity for a strategic partnership with the United States," he said.
Washington has been insisting that India needs to complete the processes required for the deal, saying time was running out in the light of the Presidential elections later this year.
New Delhi needs to firm up a safeguard agreement with the International Atomic Energy Agency (IAEA) and secure changes in the guidelines of the 45-member Nuclear Suppliers' Group (NSG) to enable international nuclear commerce with it. But stiff opposition from Left allies has tied the government's hands in moving fast on the deal.
Addressing a Heritage Foundation seminar, Padilla said, "The benefits for India are clear, and we hope that India's government will choose to move forward as quickly as possible to fully realise the potential of this historic agreement".