The tussle between Dr Singh and some party leaders, who do not want an early general election provoked by the withdrawal of Left support, is on and far from over, the Congress sources added.

Dr Singh would like to resign as prime minister if the Congress party does not back him on the deal. However, negotiations between Dr Singh and the party continue and the final verdict is not out yet.

The prime minister is likely to continue pressurising the Congress leadership before the next United Progressive Alliance-Left parties meeting on the nuclear deal on June 25.

Dr Singh will not have much to lose if he insists on an exit from power because his four-year tenure has ensured his place in history. The final year in power will be the most difficult with international oil prices likely to cross $150 per barrel.

Another factor behind the current political drama in New Delhi over the nuclear deal is a powerful lobby's belief that a strategic partnership with the United States is a win-win situation for India and the US. Dr Singh's supporters think it is time "the Congress calls the bluff of the Left parties" and goes ahead with the nuclear deal.

But it seems difficult for Dr Singh to garner his own party's support for the deal. Notwithstanding the public stand of UPA allies like Rashtriya Janata Dal leader Lalu Prasad, Nationalist Congress President Sharad Pawar [Images] and Dravida Munnetra Kazagham supremo M Karunanidhi supporting the deal, the Congress is well aware that these allies do not want an early election, and certainly not in November. External Affairs Minister Pranab Mukherjee, the mediator between the Congress, the Left parties and its allies, briefed Dr Singh on the issue today.

Dr Singh cancelled all his appointments for Thursday, June 19. An official statement said the prime minister is unwell and running a viral fever.

The prime minister is understandably anguished because it will be embarrassing for him to travel to Tokyo next month for the G-8 summit -- where he will meet US President George W Bush [Images] -- after suffering a domestic political defeat on a diplomatic issue of great importance. "The prime minister," a reliable Congress source said, "wants to save his prestige in an international forum."