As US Secretary of State Condoleezza Rice left for India, suspense mounted over the prospects of the landmark agreement being signed on Saturday with the Bush administration saying the specifics of making it a law was still being worked out.
Rice will meet the top leadership in India and discuss the civil nuclear initiative besides other bilateral issues.
Meanwhile, there was no word yet on when President George W Bush will sign the bill, approved by the Congress, into a law.
Sources said prominent members of the Indian-American community have been informed by the White House that they will be invited for the event.
"I don't have all the details of ... what happens next. I mean, the important thing is that the agreement was approved by the Congress. We can, you know, update you if you like on that at some future point," State Department Spokesman Robert Wood said.
Maintaining that the most important thing was the passage of the nuclear deal, he said the accord was good for both India and the United States and for non-proliferation efforts worldwide.
Asked about the next step on the deal, he said: "I honestly don't know all of the specifics of that. We can try to get you something on that and see if there is anything there.... Implementation is very important.
"It's only about two days give us a little time," Wood said in reference to the Senate passage of the approval legislation on Wednesday night.