State Congress president Adhir Chowdhury, following the meeting, said talks on seat-sharing between the two sides are likely to conclude by the end of the month.
The Congress had won 44 seats in the 2016 assembly elections but 18 of its MLAs have switched over to the ruling TMC since then.
According to Congress sources, whosoever takes over as PCC chief also needs to take forward the alliance.
A stalwart in Bengal politics, Mitra's political career began during the tumultuous '60s as a student leader and spanned over five decades.
Earlier, Banerjee had criticised opposition parties in the state for spreading 'political pollution' and accused the CPM and the Congress for 'politically surrendering' before the BJP.