"Knowing the Congress, they will do anything to remain in power. Let them try," said CPI(M) General Secretary Prakash Karat in New Delhi.

Asked about the Left parties' relationship with the Congress in future, he said "our decision today (to withdraw support) should make that clear."

Flanked by the General Secretaries of the four Left parties - A B Bardhan (CPI), T J Chandrachoodan (RSP) and Debabrata Biswas (Forward Bloc), Karat said the UPA government would "not be able to fight communalism with the policies they have been pursuing".

With the Samajwadi party, whose 39 members are crucial for the government's survival, stepping in after the Left withdrew support, the ruling coalition whose strength has been reduced to 230 is expected to be three short of the magic figure of 272.