Calcutta, March 4: A row over Rajya Sabha seats appears to have helped the CPM divide the mini-front of the Forward Bloc, RSP and the CPI, which had been opposing the Big Brother on industrialisation and land acquisition.

Three MPs of the CPM are going to finish their terms this month along with Forward Bloc general secretary Debabrata Biswas and the Trinamul Congress’s Dinesh Trivedi.

Polls to five Rajya Sabha seats are due in Bengal.

The CPI today iterated its demand for a “sure seat” in the Upper House, apparently at the cost of Biswas. The Bloc and the RSP rejected the idea.

So, unlike earlier meetings where the CPM drew flak from its allies, the Left Front session on Thursday is likely to see the Big Brother brokering peace among them.

“We want a secure seat and the CPM leadership has admitted the legitimacy of our demands as we have not had any representative in the Rajya Sabha from Bengal for over a decade,’’ CPI state secretary Manju Majumder said.

“Left unity and not the strength in the Assembly should determine who sends a representative from the state,” he added.

The CPI has seven MLAs, compared with the Bloc’s 23 and the RSP’s 17.

Bloc veteran Ashok Ghosh has been insisting on another term for Biswas, who has already served three terms of six years in the Upper House.

The CPM wants the Bloc to ask another MP, Barun Mukherjee, to step down after he completes three years in 2009 to make room for the CPI. Mukherjee’s term is scheduled to end in 2012.

“We can’t wait till 2012,’’ Majumder said.

Bloc state secretary Ghosh will meet the CPM brass tomorrow. His RSP counterpart Debabrata Bandopadhyay met CPM state secretary Biman Bose yesterday.

The RSP and the Bloc have come together to “protect their common interests”.

According to them, the second and third-largest front parties are entitled to a “permanent” Rajya Sabha seat. The two parties share the other seat by rotation.

The Bloc’s Barun Mukherjee now occupies it. RSP national spokesman Abani Roy and the Bloc’s Biswas now hold the parties’ “permanent” seats.

The arrangement was formulated by first front chairman Promode Dasgupta, said Ghosh.

“Biswas will file his nomination and Mukherjee won’t step down,’’ Bloc leader Naren Chatterjee insisted.

“The CPM is trying to break our resolve to go it alone in the panchayat polls by instigating the CPI,” he added.

An RSP leader also said the CPI “has fallen into the trap”.

The two parties want the CPM to leave one of its three seats to the CPI as it had done earlier. They also suggested that the CPI may contest the fifth seat as Trinamul’s Trivedi is unlikely to win if the Congress decides not to support.