The Chairman of India's Atomic Energy Commission Dr Anil Kakodkar, who is in the United States with a high-powered delegation led by National Security Advisor M K Narayanan, will not meet American lawmakers and will not make any public appearance, diplomatic sources told rediff.com.

He will largely play a behind-the-scenes role and will sit in on the high-level meetings between the US and Indian teams so as to ensure that India's strategic and nuclear establishment's interests are not compromised while implementing the civilian nuclear agreement.

This comes as a disappointment for the groups that have been lobbying in the Congress.

These groups wanted Kakodkar to meet some leading Democrats who are against the deal and assuage them that India will not use American nuclear fuel supplies to beef up its nuclear weapons arsenal.

The sources said having Kakodkar during this round of talks, which could be the one where finally a deal is struck, is to assure that the scientific establishment is also on board.

Meanwhile, just before Kakodkar landed, Foreign Secretary Shiv Shankar Menon and Narayanan were in a closed-door roundtable with leading policy analysts and US lawmakers like Congressman Gary Ackerman, one of the co-authors of the enabling legislation to facilitate the US-India nuclear deal.

He was not in on the talks between the teams led by US Undersecretary of State Nicholas Burns -- the chief US interlocutor -- and Menon at the State Department on Tuesday, either, although his representative R B Grover was present.

Kakodkar, however, was present at the working dinner hosted by Burns on Tuesday, and would be a significant protagonist at the talks between Narayanan and Burns his counterpart in the White House, National Security Adviser Stephen Hadley, where a deal -- if there is one to be had on the 123 Agreement -- would be signed on Wednesday.

Kakodkar's presence is significant because some US lawmakers perceive him to be the "600-pound gorilla in the room," and the final arbiter of whether there would be a deal if India's concerns are not met.