Jeopardized by an Indian political squabble, the landmark U.S.-India nuclear deal — one of President Bush's top foreign policy priorities — is at risk of being left to an uncertain fate when the next president takes office in January.

The three contenders to replace Bush — Democrats Hillary Rodham Clinton and Barack Obama and Republican John McCain — endorsed legislation in late 2006 that would reverse three decades of American anti-proliferation policy by allowing U.S. shipments of civilian nuclear fuel to India.

The pact faces fierce opposition in India, where communists who support Prime Minister Manmohan Singh's coalition continue to bar it. The next U.S. president could revive Bush's coveted deal if it should fail this year, but it is not clear that any of the candidates would consider it a priority. Also, the new administration would be working without many of the high-level Bush officials who led painstaking talks with India and then persuaded skeptical U.S. lawmakers to approve the deal.

"It just becomes much more burdensome, because the principal players who were involved in the negotiations will have moved on; there will be a loss of collective memory," said Ashley J. Tellis, a senior associate at the Carnegie Endowment for International Peace who has advised McCain's campaign on Asia issues. "It's entirely possible, for someone who doesn't like the agreement, to simply say, if they were to come into office: 'Thank you very much; this is the policy of the last administration; I don't want to have any part of it.' "

The new pact would give India access to U.S. civilian nuclear technology and fuel in exchange for India's allowing safeguards and international inspections at its 14 civilian nuclear installations. Eight self-designated military plants would remain off-limits.

The pact is portrayed by Bush as the cornerstone of what he hopes will be a new strategic relationship with democratic India, a growing economic and military power in Asia with what Bush considers a responsible nuclear program. Some see a strong India as a possible counterweight in the region to China. Critics say the deal would ruin global efforts to stop the spread of atomic weapons and boost India's nuclear arsenal.

The United States says India must approve the agreement soon if Congress is going to have enough time to take it up again before lawmakers leave for a break in August and then begin campaigning for the November elections.

"Time is running out," the State Department warned on Thursday.

After recent meetings with Bush and Secretary of State Condoleezza Rice, however, India's foreign minister could offer no assurances that his government was close to settling its differences. Indian communist parties, which are crucial to the survival of Singh's government, have threatened to pull their support if Singh should try to complete the deal.

State Department spokesman Tom Casey held out the possibility that the deal could be finished even if it bogs down this year. He told reporters Thursday that "there would be opportunities in future Congresses and with the future administration to move forward on this."

"Regardless of whether this arrangement is passed in the next year or not, one thing that I don't think will change is the continuing strengthening and deepening of the U.S.-Indian relationship that has begun under this administration and we certainly hope will continue into the future," Casey said.

Jon Wolfsthal, an analyst at the Center for Strategic and International Studies think tank and an adviser to the Clinton campaign, says that if India should fail to act this year, "It's unlikely that any of the (U.S.) candidates will be anxious to resubmit this or push this ahead."

The Bush administration, Wolfsthal said, wanted to win over India as "a strategic military partner to help contain China." McCain, Clinton and Obama, he said, do not have the same drive to settle the deal.

Tellis, however, says a President McCain could support the Bush policy to use the nuclear deal as the foundation of new, stronger ties with India.

Obama and Clinton, though, "were very uncomfortable supporters of the agreement," he said, and would be less likely to embrace it as president. Tellis served as an adviser to former Undersecretary of State Nicholas Burns, a top negotiator on the deal.

Burns' recent departure from the administration was another blow to the agreement, although Rice has said he would remain involved even after he left.

Final passage of the deal would set up a major shift in U.S. policy. India has been shunned by the world's nuclear powers since it conducted its first underground nuclear test in 1976.