The “breakthrough” in the talks between the Congress and the Left came about through the intervention of Rahul Gandhi, a senior Bengal Congress leader said on Saturday.

The state Congress leader said that following the party’s decision to give up the claim on the Raiganj and Murshidabad seats, former Raiganj MP Deepa Das Munshi was likely to be sent to the Rajya Sabha from another state.

Behrampore MP Adhir Chowdhury had earlier indicated his willingness to withdraw the party’s claim on the Murshidabad Lok Sabha seat, according to state Congress sources.

Out of the 42 Lok Sabha seats in Bengal, the Congress is expected to contest in 17 seats and the Left Front 25.

“This is a big breakthrough…. All thanks to Rahul Gandhi,” said a state Congress leader in favour of the alliance. “For hours on Friday night, Rahul and his team kept at it. He had clearly made up his mind to finalise this within this week before the poll panel announces the general election,” the state Congress leader added.

Sources said Rahul would launch the Congress’s Bengal campaign with a rally in Malda’s Chanchol on March 23.

The Left Front had announced on Friday that the CPM’s victorious MPs from 2014 — Mohammad Salim from Raiganj and Badruddoza Khan from Murshidabad — would be fielded again this year. But the door was left ajar on a seat-sharing understanding with the Left not fielding candidates in the four seats the Congress had won that year.

“Rahul himself has been serious about this alliance, which is being stitched together for lasting at least till the Assembly polls of 2021…. The AICC did not want all of it to fall apart over just two seats that we had lost anyway,” said a state Congress leader.

In the Assembly polls of 2016, the Congress and the Left had entered into an informal understanding. The alliance did not work for the Left on the ground.

While the Congress had won 44 seats, the Left had bagged 33. Trinamul had won 211 seats in the 294-seat Assembly, which has gone up to 232 now with the crossover of 18 Congress and three Left MLAs.

“It is not for the number of seats in the short term that this is being done for…. Even in 2016, the vote share of the alliance was over 38 per cent (around 26 per cent for the Left and over 12 per cent for the Congress) when Mamata (Banerjee) got around 45 per cent,” said a CPM leader.

“A key aspect will be the erosion this will cause in the BJP’s vote share here,” he added.

This time, the agreement is expected to be a formal one on the seat-sharing. It will be in keeping with the Congress state unit’s stand in favour of equidistance from both the BJP and Trinamul in Bengal, irrespective of Mamata’s equations with the Congress’s national leadership.

“The finer details are yet to be worked out. For instance, which 13 seats, other than the four we won in 2014, will be for us to contest. Who the candidates will be…. There are some discussions within the party and with the Left that remain, after which the announcement would be made formally,” said a state Congress leader.