The United States has reassured India it would try its best to get the landmark nuclear deal approved by a "lame duck" session of Congress next month amid fears that the agreement could be slipping away.
The assurance was given by US Secretary of State Condoleezza Rice when she called External Affairs Minister Pranab Mukherjee late on Wednesday to congratulate him on being named to the position, an Indian official said on Thursday.
"She said the administration was talking to senators and would do its best to get their approval in this session," the official said.
The deal, which aims to overturn a three-decade US ban on supply of nuclear fuel and equipment to energy-hungry India, has been stuck in the US Senate after the chamber failed to vote on it in September due to disputes between the Republicans and the Democrats.
Congress is due to sit for a "lame duck" session early next month after elections to both chambers. If the Senate does not pass it then, the deal will have to start a long and winding approval process in both chambers from scratch.
Although Washington has said the deal, symbolic of the new friendship between the once-estranged democracies, enjoys bipartisan support, analysts are sceptical.
They say if the Democrats win control of Congress as expected, they are unlikely to allow the passage of any significant legislation in the "lame duck" session.
The deal has been dogged by controversy since it was first agreed in principal between Bush and Prime Minister Manmohan Singh in July 2005.
The non-proliferation lobby in the United States says it gives away too much to India, which has not signed the Non-Proliferation Treaty and has conducted nuclear tests.
The communist parties, the Bharatiya Janata Party and some nuclear experts have also criticised it, saying Washington was seeking to curb India's nuclear programme by imposing restrictions as part of the deal.
Anil Kakodkar, head of India's Department of Atomic Energy, who initially opposed the deal but now supports it, said New Delhi would be forced to pursue alternative energy sources that may not be eco-friendly if the deal did not go through.