"Their alliance will continue", she said, adding that such a fight can be effectively fought by a simple rule, that the opposition party which was the strongest in a state should be supported by the others to oust the BJP.
Banerjee, who is in Delhi since Tuesday, said that the Congress should help the "anti-BJP" front. "We want the Congress also to be part of that", she said.
The Congress on Thursday said that it will welcome all parties who are ready to sink their ideological differences to work together with it for a united fight against the BJP.
Addressing media after meeting, Mamata Banerjee said that whenever I come here I meet her, we share a good relation. I suggested her that in 2019 elections, there should be one-is-to-one fight to eradicate BJP.
After Mamata Banerjee's round of hobnobbing with opposition party leaders in Delhi, it will be the turn of Telegu Desam Party (TDP) leader and Andhra Pradesh chief minister, N Chandrababu Naidu's to connect with the opposition group next week.
Ms Banerjee further added, "I am 100 per cent sure that when there is one fight, the BJP will go". I said that the country required a one-on-one contest in 2019.
Mayawati exposed the "double standards" of BJP in dealing with similar situations in states where it was in power and in states where it was not. "We will not get time for campaigning if the polls are conducted in the first week of May".
She said an alliance will depend on the concerned parties.
However, the BJP targeted the TMC supremo over the incidents of violence during Ram Navami processions in West Bengal, saying while her state was "burning", she was "doing politics" in the national capital.
The TMC leader also met Delhi chief minister Arvind Kejriwal.
After West Bengal administration rejected Centre's proposal for paramilitary forces to deal with communal strife in parts of south Bengal, the state government proposed Election Commission to hold the upcoming panchayat elections in the state without any central forces stating that its 56,000 state forces would be adequate to conduct the elections.
Naidu's hopes of a no-confidence motion against the NDA in the Lok Sabha were dashed on Wednesday after the Lower House was adjourned till 2 April.
Surjewala also struck a cautious note and asserted that the Congress held Mamata in high esteem.