Three leading U.S. senators have told India's prime minister his government has only weeks to finalize a civilian nuclear deal with the United States or senators in Washington will not have time to ratify the agreement. It is the strongest and most specific warning India has received that time is running out for it to decide the fate of the controversial deal. VOA Correspondent Steve Herman reports from New Delhi.

Between visits to Pakistan and Afghanistan, Senators John Kerry, Joe Biden and Chuck Hagel stopped in New Delhi to tell Prime Minister Manmohan Singh that little time remains to conclude the civilian nuclear-fuel agreement between the United States and India.

India remains locked in talks with the International Atomic Energy Agency, which needs to approve a safeguards agreement for the deal to go through. India also must obtain a waiver from the 45-nation Nuclear Suppliers Group before the pact can go to the U.S. Senate for an up-or-down vote. The group oversees the export and re-transfer of nuclear materials.

Senator Kerry, the South Asian Affairs Sub-Committee chairman, explained to Mr. Singh and other top Indian government officials the U.S. Senate's schedule in a presidential election year means lawmakers in Washington face critical time constraints.

"In order to be able to have time to debate this and pass it in the Senate, it would really probably have to be received somewhere in May, at the latest, in order to give time to be able to pass," he said. "So I think somewhere in the next weeks some kind of decision has got to happen because we are just going to run out of time."

Biden, who leads the Senate Foreign Relations Committee, predicted that if either of his Democratic Party's contenders for president, Senator Hillary Clinton or Senator Barack Obama, win the White House, the deal would certainly have to be renegotiated. He said Democrats are moving towards - and not away from - stricter controls on nuclear proliferation.

U.S. lawmakers opposed to the deal have argued it could strengthen India's nuclear-weapons arsenal and trigger a regional arms race.

Biden says Prime Minister Singh told the three senators that he has run into domestic political obstacles.

"He explained his difficulties to us. He indicated he was going to pursue the effort," he said. "We were wise enough not to ask him any more than he would ask us. Precisely what he would do and how he would do it, when he would do it, and what his coalition would do. But we walked away with a sense that he valued the agreement still and he still wanted the agreement."

Prime Minister Singh made no public comment on the warning delivered by the senators.

The three senators also expressed concern that the deal's failure could mean the Indo-American relationship will suffer, with Indians mistakenly blaming the collapse of the landmark agreement on the U.S. Senate.

Both governments have touted the nuclear deal as the centerpiece of a new era in relations between Washington and New Delhi. But India's domestic opponents to the agreement contend it will bring India too close in strategic alignment with the United States. Some also feel it impinges on India's sovereign right to test nuclear weapons free of foreign restrictions.

The pact would give India access to American nuclear fuel and reactors. Such international cooperation has been out of the question since India set off atomic weapons tests in 1974 and again in 1998, and refused to sign treaties on non-proliferation and nuclear testing.