The Left parties on Wednesday withdrew support to the United Progressive Alliance government.
Leaders of the four Left parties, led by Communist Party of India-Marxist general secretary Prakash Karat, handed over letters of withdrawal of support to the four-year-old UPA government to President Pratibha Patil just after noon.
President Patil told the Left delegation that she would discuss the matter with Prime Minister Manmohan Singh on his return from Japan and then take a decision.
A Rashtrapati Bhavan official said no time frame could be set for the President's decision.
In a joint letter, the Left delegation said: 'In view of the withdrawal of support by the Left parties to the Manmohan Singh government, we request you to direct the prime minister to seek a vote of confidence in Lok Sabha immediately.'
The four Left parties have 59 members in the Lok Sabha.
"We have met the President and have given her a letter on behalf of the four Left parties withdrawing support to the UPA government," Karat told media persons later.
Following the withdrawal of support by the Left parties the strength of the ruling coalition has been reduced to 230.
Samajwadi Party, which has 39 MPs in the Lok Sabha, has announced support to the government, which still leaves the
ruling UPA three members short of majority.
UPA managers are claiming that as of now the government could count on the support of at least 273 members in the Lok Sabha, which currently has 543 members. There are two vacancies.
A confident Prime Minister Manmohan Singh, whose announcement that India will very soon approach the International Atomic Energy Agency for the safeguards agreement triggered the Left's break up, had said the Left's decision will "not affect the stability of the government."
The talk of unease among some MPs in the Samajwadi Party in joining hands with the Congress has triggered speculation that the party may not have the backing of all the 39 MPs. But SP leader Amar Singh claimed all the members will vote for the government.
Nationalist Congress Party chief Sharad Pawar and Rashtriya Janata Dal supremo Lalu Prasad Yadav claimed that the UPA has numbers on its side to win a confidence vote.
The ruling side is banking on three independents -- Thupstan Chhewang from Jammu and Kashmir, Harish Nagpal from Uttar Pradesh and Charenamei Mani from Manipur.
The three-member Rashtriya Lol Dal is also being seen as a supporter of the ruling side with Ajit Singh having a meeting with Congress president Sonia Gandhi sometime back.
Congress is also hopeful that former prime minister H D Deve Gowda's Janata Dal-Secular, which has three MPs may vote for the government.
Another fallout of the break in ties between the UPA and the Left parties will be the exit of Lok Sabha Speaker Somnath Chatterjee from the post. Chatterjee is a CPM member of Parliament.
Additional Reportage: PTI