Congress Bengal unit had earlier recommended an alliance, which was also favoured by Left parties. (File)
The Congress and the Left have joined hands in Bengal to challenge the Mamata Banerjee government, which is seeking a third straight term in next year's assembly elections. Senior state leader Adhir Ranjan Chowdhury announced the Central leadership's approval to the state unit's request this afternoon.
"Today the Congress high command has formally approved the electoral alliance with the Left parties in the impending election of West Bengal," Mr Chowdhury posted on Twitter.
The party's Bengal unit had earlier recommended an alliance, which was also favoured by the Left parties.
The two parties had contested the 2016 polls together in the state to take on Mamata Banerjee's Trinamool Congress, which had swept out the 34-year rule of the CPM in the state just five years ago.
But the Left-Congress alliance failed to make much of an impact, managing to win only 74 seats of the state's 294 seats. The Congress did somewhat better than its allies, winning 44 seats, the CPI(M) could only get 26.
The alliance did not start out with the blessings of the party's Central leadership, in view of the situation in Kerala, where the two are traditional rivals.
The Left, which was in the opposition in Kerala at the time, did not wish to ruin its chances in the state election two years down the line. Kerala has a longstanding record of voting out the incumbent party.
Last year, the Left and the Congress did not contest the Lok Sabha elections in Bengal together, even though they were part of the loose anti-BJP opposition bloc nationally. Mamata Banerjee's Trinamool Congress also was on the same side, with Ms Banerjee being one of the main proponents of forming an anti-BJP wall – a plan that did not take off.
This time, the BJP is the main challenger to Ms Banerjee and the party has claimed that it would form the next government in the state. Union minister and former party chief Amit Shah has set the BJP state unit a target of 200 seats. The party had failed to meet the mark in 2016, two years after the BJP's sweeping victory at the Cente.
This time it hopes to win in spades, buoyed by its performance in the last year's Lok Sabha elections, where it won 18 of the state's 42 seats.
Assembly elections in Bengal are due by March or April next year.