Instead of his regular constituency Bolpur, the Speaker will be contesting the next elections from Birbhum, said sources at Alimuddin Street, CPM's state headquarters.

As per new guidelines, Bolpur, a CPM stronghold, has been declared a reserved seat for the Scheduled Castes. Birbhum, a reserved seat till the 2004 elections, has now been converted into a seat for general candidates.

The CPM leadership in Kolkata is learnt to have instructed its Birbhum district committee to leave no stone unturned in ensuring that Chatterjee is elected.

Historically, CPM's performance from Birbhum has not been as strong as it has been from Bolpur. “If the opposition vote in Birbhum is united, the party will be left with only a 2 per cent margin, since in 2004, CPM garnered 51 per cent of the votes polled,” said a senior leader. Plus, “a lot of factors like Nandigram, Singur, and resentment from a section of Muslim voters, have gone against the CPM. Taking these things into account, the party's election machinery in the constituency (Birbhum) will have to be further strengthened,” he added.

The secretary of Birbhum district committee of the CPM, Dilip Ganguly, said: “There is no doubt that if Somnath Chatterjee contests from Birbhum he will win. But the party is yet to declare his candidature.”

According to CPM sources in Birbhum, Bolpur has been classified as a reserved seat due to the annexation of Ketugram Assembly segment, which is dominated by the Scheduled Castes.

“The Bolpur constituency now consists of an additional three per cent SC voters,” said Ganguly.

Chief Election Officer of West Bengal, Debashish Sen, however, said the decision to classify Bolpur as a reserved seat was not based on the increase in the number of SC voters.