Kolkata: Taken aback by the drubbing the Left Front-Congress alliance received in the West Bengal assembly polls, two opposition leaders, who played a key role in forging the unlikely pact, on Thursday blamed the "adverse political atmosphere" and the "selective transfer of BJP votes in specific constituencies" for the electoral debacle.

Admitting that the alliance had "failed to reach out to the people the way it was desired", CPI-M politburo member Mohammed Salim said: "We have to ponder over that."

"However, the adverse condition under which we had to fight also needs to be taken into consideration. We have not been able to bring things to our favour but out fresh struggle would be to find out how that can that be done."

Salim had been one of the star campaigners for the alliance throughout the state. He addressed the second highest number of election meetings for the Left Front after Communist Party of India-Marxist secretary Surjya Kanta Mishra.

Asked if the party was still groping in the dark to find the reason for its continued electoral setbacks since 2011, Salim said: "We have found the reason but just by identifying the malady, does a patient get healed?"

State Congress general secretary Om Prakash Mishra, another architect of the alliance, called the result "very disappointing".

Mishra had in February written two letters to the party high command claiming it would win 170 of the 294 seats.

On whether the problem lay in the Congress and the Left Front failing to transfer the votes to each other, Mishra replied in the negative. "The Congress, LF vote transfer was achieved."

Mishra pointed to two factors.

While acknowledging that Chief Minister Mamata Banerjee's development schemes have been a hit among the people, the political science professor pointed fingers at the BJP as well.

"In some specific constituencies, there was a selective transfer of BJP votes to the Trinamool. We have to look into it."

Queried whether he saw any design in that, Mishra replied: "could be. We can say (that) more certainly once we analyse the detailed results."

Mishra had before the elections predicted that 40 percent of the 17 percent votes the BJP obtained during the 2014 general elections would shift to the alliance.

Though the BJP's vote share has seemingly dropped, the alliance has not benefited from it. In fact, initial analyses showed that the Trinamool has benefitted in many areas from the BJP's loss.

However, Mishra said the Left and the Congress should continue their alliance.

"The politics and the policies we have advocated remain relevant. There is no reason for the alliance not to continue. On the contrary, it should be further strengthened in Bengal."