A strong Third Front sans Congress and Bharatiya Janata Party at the Centre was necessary since the country was passing through a "critical" phase, Communist Party of India general secretary A B Bardhan said.
"The Third Front alternative is necessary, but it cannot be achieved by meeting with some leaders only," he said reacting to Communist Party of India-Marxist general secretary Prakash Karat's recent meeting with the Samajwadi Party supremo Mulayam Singh Yadav.
He said it could be only possible through strengthening of Left democratic forces and people's movement.
The veteran CPI leader attended the birth centenary celebration of former party leader Dandapani Swain at Gautami, around 30 km from Berhampur.
Reiterating that Left's support to United Progressive Alliance government was not for all times to come, Bardhan said it depended on how the government strictly adhered to Common Minimum Programme formulated by UPA allies.
"We have given support to the UPA on the basis of CMP prepared at the time of 2004 election and to keep fundamentalist BJP at bay," he said.
Any deviation from the CMP would not be tolerated, Bardhan warned adding, the Centre had violated the CMP on economic and foreign policy front.