"Supporting the Congress is ruled out unless Rahul Gandhi declares himself a socialist and has a new economic manifesto," Karat told 'Outlook' magazine in an interview.
According to a release issued by the news magazine, Karat was responding to a question whether the Left party would support the Congress on the 'secular principle' in the event of the BJP emerging as the single largest party in the next general elections due in 2014.
The Left parties, led by the CPI(M), had withdrawn support to the UPA-I government in the wake of the Indo-US nuclear deal in 2008.
The interview has come at a time when the CPI(M) has endorsed Pranab Mukherjee as the UPA candidate in the Presidential poll and has indicated a comfort level with Vice President Hamid Ansari being again renominated for the job.
Asked about Mulayam Singh Yadav's recent political moves, Karat struck a lighter note remarking "he thinks there is a serious possibility (that) he could become the PM".
He also ruled out any attempt by the Left to forge a third or fourth front.
"We see the growth of regional parties as a positive development. But at the same time, it is difficult to form a coherent all-India front. That is why we are not interested."
Karat also added "the need is there, but it is unreal to think of a third front".
New Delhi: CPI(M) General Secretary Prakash Karat has ruled out extending support to Congress after the next Lok Sabha elections "unless Rahul Gandhi declares himself a socialist".
First Published: Friday, July 13, 2012, 22:13