Meanwhile, the UPA government, which appeared unfazed and declared that it would seek a vote of confidence in the Lok Sabha during a short session this month after which it will move to operationalise the Indo-US nuclear deal.

Ending their four-and-a-half year acrimonious relationship with the Congress over the nuclear deal, the four Left parties with a total of 59 MPs will formally announce their withdrawal at 12 noon tomorrow when they will meet President Pratibha Patil.

The Left's decision, as expected, set off a flurry of political maneouverings with the government, which has 230 members in the Lok Sabha without the Left, asserting that it had the required majority of at least 272, the gap being filled by 38 Samajwadi Party MPs plus support from smaller parties such as PDP.

A confident Prime Minister Manmohan Singh, whose announcement that India will very soon approach the IAEA for the safeguards agreement triggered Left's break up, said the Left decision will "not affect the stability of the government".

Singh, who is in the Japanese island of Sappro, said, "We will go to the IAEA as soon as possible."