"With India's 34-year nuclear isolation now history, the opportunity for US companies today is tremendous, with a potential $150 billion of new investment. If US companies are allowed to compete, a modest share of that business could support 2,50,000 high-tech American jobs," Chamber Chairman R Bruce Josten said in a letter to all Senators and Representatives.

In the Chamber's estimation, US companies could greatly benefit from India's expected 30,000 to 60,000 MW of new nuclear generating capacity by 2030.

"Moreover, the nuclear business would be a fraction of the broader commercial gain across all sectors after this foundation, established of mutual trust and respect, is laid," Josten said and referred to the fact that it was the General Electric which made the first reactor for India's civil nuclear programme back in 1961.

The US Chamber, which happens to be the world's largest business federation representing more than three million businesses, sought to allay fear among lawmakers over any undue delay in passage, saying: "It is crucial that Congress act. French and Russian firms are already working in India, yet US firms cannot engage until Congressional approval of the 123 Agreement."