Indian communists are not expected to soften their position over a nuclear deal with the United States at a meeting on Wednesday of a panel that aims to resolve their row with the government, left leaders said.

The panel, consisting of senior government leaders and communist representatives, was formed last month after the left parties warned Prime Minister Manmohan Singh's coalition of "serious consequences" if it did not dump the historic pact.

Opposition to the deal by the communists, whose support is key to the survival of Singh's coalition, has led to the worst political crisis since the government was formed in 2004 and sparked fears of a general election before it is due in 2009.

The deal aims to give India access to American nuclear fuel and equipment to help meet its soaring energy needs even though it has tested nuclear weapons and not signed the Non-Proliferation Treaty.

But communists say it hurts India's sovereignty and exposes the country's foreign policy to Washington's influence. They have threatened to end their support if the government pursues negotiations needed to secure global approvals for the deal.

The panel held its first meeting last week and the two sides subsequently exchanged notes, with the government replying to concerns raised by the communists.

The communists were preparing a "rejoinder" to the government's reply ahead of Wednesday's meeting, Nilotpal Basu, a lawmaker and a senior leader of the Communist Party of India (Marxist), told Reuters.

"On many of the issues which are relevant, particularly those pertaining to energy policy, the defense of the government is very weak," he said.

On Tuesday, CPI(M) chief Prakash Karat urged the government not to pursue the deal for six months and warned of a "political crisis" if it went ahead.

While the Indian government is yet to respond to that demand, U.S. officials have reaffirmed that time was running out on the deal as Washington would be preoccupied with presidential elections next year.

"They are trying to put pressure on us," said A.B. Bardhan, head of the Communist Party of India, the second largest of the four left parties who together have 60 MPs in the 545-member lower house of parliament.

"They have their own timeframe, we have our own, but the government should not succumb to them," he said.

Government leaders say they hope to convince the communists and allay their concerns through the panel. But analysts are not confident as left leaders seem to remain adamant.